Hey! Â I've got an idea! Â Let's list some existing IPs that would make good MMORPGs that might seem a little surprising, some of the reasons why, along with some of the detriments to them. Â I'll kickoff.
Armored Core (From Software)
Armored Core was a game about mecha that was, essentially, the best sci-fi RPG I ever played. Â I brought this up yesterday with some friends, and instead of people coming after me because they thought it wasn't the best, it seemed like most people didn't think it's an RPG. Â Really, though, it is. Â Armored Core revolved around tough decisions to obscure stats that could make or break your rig WAY before it was a thing when EVE did it (which is probably why I don't get why people think gearing in EVE is such a hassle). Â So much variation and lateral movement.
The biggest issue I see with it? Â MMORPGs operate best on an individual level, Armored Core puts you into a gigantic suit of armor. Â That will either definitively separate "town" from "game world" because one will be interacted with in-person and the other would be interacted with in the suit. Â It might also limit setting, because the suits will be huge. Â There's no "explore the cave" thing when you're in a massive machine. Â Still, I can see it being done well, especially if the setting becomes much more vast.
Mega Man Legends (Capcom)
Also had a discussion about this recently. Â A long discussion. Â As in a discussion triple-damning Capcom's soulless and idiotic business management team for killing their new Mega Man Legends game because people don't want to pay 40 dollars for a demo. Â Regardless, in case nobody knows, Capcom made an amazingly good RPG series using their Mega Man IP. Â Which, I know, sounds ridiculous. Â Hear me out, though.
Mega Man was a crazy sci-fi setting you can barely make anymore, in that it could be somewhat dark but wasn't dripping with head-slapping moral ambiguity. Â Best of all, it was a REALLY good game, especially mechanically. Â The greatest strength of the IP is in the name itself. Â They could throw goofy swords, trains, and what have you in there, but I guarantee you that EVERYONE that grew up with that game came up with a few insert-cool-name-here-man ideas. Â Imagine being able to gear up your own sentient robot with lightning weapons, dust weapons, and the like, and to power your own buster or sword.
I mean, the detriment is that it might be hard to pull off correctly. Â It's not going to target the most nasty demographic, and that seems to be what the MMORPG market aims at, but I really think Capcom's developers could pull that off and make it memorable.
They won't because their business branch sucks, but I swear it could work.
Crimson Skies (Microsoft Game Studios as far as I know)
Crimson Skies, for those who don't know, is a game set in an alternate dieselpunk reality of the 1930s where old-fashioned planes and zeppelins became a sort of recreation of the golden age of piracy. Â Obviously, the major drawbacks might be the same as the Armored Core game, that you'd need to get out of the plane to have a "city" and in this case most of the scenery would be passing by beneath and around you most of the time instead of being directly experienced.
However, I can see this working. Â Considering the scenery is just that... scenery, you could REALLY get away with making the overworld huge. Â It would also mean you might be able to really do land development like you can't do in other games, because you'd need so much blank land to make the game work, you could probably drop private bases all over the place and put hidden airstrips everywhere. Â It'd be difficult to design, but I think the pros might outweight the cons there.
On a related note...
Descent (Interplay Studios)
Descent was a bit like Doom back in the day it was released... only that you flew around in a small spaceship. Â The one game where you had to deal with complete freedom of motion, I loved the sense of vertigo you'd get floating around. Â It's the one flying game that might give you the option of both dogfighting at high speed and entering a dungeon setting. Â I know Interplay re-registered the trademark.
Problems are similar to Armored Core and Crimson Skies above, that you might not be able to have a "town" per se unless you disembarked, but that's not as distinct of a problem here. Â Descent was always more maneuverable and personable than those other games. Â It might work out.
Starcraft (Blizzard)
This might not seem like such an oversight.  Blizzard owns the MMORPG that still reigns above them all as their crowning achievement  years after the game had become graphically and conceptually archaic.  They are working on a new project even now that had to be developed to such exacting standards that they essentially erased all they had at one point in disgust.  And yet, I recall being disappointed when the only hard information we had on their Titan project was that it wasn't essentially going to be World of Starcraft.
Disappointed, because I once had a long, drawn out conversation with my brother wherein I essentially out-did WoW with Starcraft's potential. Â Seriously, your three factions would essentially have three different ways of leveling (Terrans using gear and skills, Zerg using character models and evolution, Protoss using techniques and crazy-squid-space-magic), almost unlimited settings as you can always add more planets to any system, and an atmosphere that can literally go from wild-west drama to Starship Trooper-style action to darkened horror within minutes. Â It's a game where you can essentially add huge amounts of lateral growth for all the races, have a metric ton of enemies to fight (it's space, after all), and balance the game in faction-specific performance rather than having to give everyone access to the same stuff.
The problems? Â They're a little harder to come up with... sometimes I think Blizz is creating a new sci-fi IP for Titan simply because a Starcraft MMORPG was almost too obvious of a good idea. Â I do see that there might be issues with it, though. Â As an IP, it's known, but it doesn't have the breadth that Azeroth's game universe had. Â Three-way faction balance on factions that operate in completely different ways might be exceptionally difficult (or not, depending). Â It might also simply be that Starcraft is only really going through it's second phase of serial development and maybe they wouldn't have wanted to really work on that idea until it was done. Â I'm not sure, but it mostly seems like Blizz looked at it and said, "You know what? Â It's too easy..."
Armored Core (From Software)
Armored Core was a game about mecha that was, essentially, the best sci-fi RPG I ever played. Â I brought this up yesterday with some friends, and instead of people coming after me because they thought it wasn't the best, it seemed like most people didn't think it's an RPG. Â Really, though, it is. Â Armored Core revolved around tough decisions to obscure stats that could make or break your rig WAY before it was a thing when EVE did it (which is probably why I don't get why people think gearing in EVE is such a hassle). Â So much variation and lateral movement.
The biggest issue I see with it? Â MMORPGs operate best on an individual level, Armored Core puts you into a gigantic suit of armor. Â That will either definitively separate "town" from "game world" because one will be interacted with in-person and the other would be interacted with in the suit. Â It might also limit setting, because the suits will be huge. Â There's no "explore the cave" thing when you're in a massive machine. Â Still, I can see it being done well, especially if the setting becomes much more vast.
Mega Man Legends (Capcom)
Also had a discussion about this recently. Â A long discussion. Â As in a discussion triple-damning Capcom's soulless and idiotic business management team for killing their new Mega Man Legends game because people don't want to pay 40 dollars for a demo. Â Regardless, in case nobody knows, Capcom made an amazingly good RPG series using their Mega Man IP. Â Which, I know, sounds ridiculous. Â Hear me out, though.
Mega Man was a crazy sci-fi setting you can barely make anymore, in that it could be somewhat dark but wasn't dripping with head-slapping moral ambiguity. Â Best of all, it was a REALLY good game, especially mechanically. Â The greatest strength of the IP is in the name itself. Â They could throw goofy swords, trains, and what have you in there, but I guarantee you that EVERYONE that grew up with that game came up with a few insert-cool-name-here-man ideas. Â Imagine being able to gear up your own sentient robot with lightning weapons, dust weapons, and the like, and to power your own buster or sword.
I mean, the detriment is that it might be hard to pull off correctly. Â It's not going to target the most nasty demographic, and that seems to be what the MMORPG market aims at, but I really think Capcom's developers could pull that off and make it memorable.
They won't because their business branch sucks, but I swear it could work.
Crimson Skies (Microsoft Game Studios as far as I know)
Crimson Skies, for those who don't know, is a game set in an alternate dieselpunk reality of the 1930s where old-fashioned planes and zeppelins became a sort of recreation of the golden age of piracy. Â Obviously, the major drawbacks might be the same as the Armored Core game, that you'd need to get out of the plane to have a "city" and in this case most of the scenery would be passing by beneath and around you most of the time instead of being directly experienced.
However, I can see this working. Â Considering the scenery is just that... scenery, you could REALLY get away with making the overworld huge. Â It would also mean you might be able to really do land development like you can't do in other games, because you'd need so much blank land to make the game work, you could probably drop private bases all over the place and put hidden airstrips everywhere. Â It'd be difficult to design, but I think the pros might outweight the cons there.
On a related note...
Descent (Interplay Studios)
Descent was a bit like Doom back in the day it was released... only that you flew around in a small spaceship. Â The one game where you had to deal with complete freedom of motion, I loved the sense of vertigo you'd get floating around. Â It's the one flying game that might give you the option of both dogfighting at high speed and entering a dungeon setting. Â I know Interplay re-registered the trademark.
Problems are similar to Armored Core and Crimson Skies above, that you might not be able to have a "town" per se unless you disembarked, but that's not as distinct of a problem here. Â Descent was always more maneuverable and personable than those other games. Â It might work out.
Starcraft (Blizzard)
This might not seem like such an oversight.  Blizzard owns the MMORPG that still reigns above them all as their crowning achievement  years after the game had become graphically and conceptually archaic.  They are working on a new project even now that had to be developed to such exacting standards that they essentially erased all they had at one point in disgust.  And yet, I recall being disappointed when the only hard information we had on their Titan project was that it wasn't essentially going to be World of Starcraft.
Disappointed, because I once had a long, drawn out conversation with my brother wherein I essentially out-did WoW with Starcraft's potential. Â Seriously, your three factions would essentially have three different ways of leveling (Terrans using gear and skills, Zerg using character models and evolution, Protoss using techniques and crazy-squid-space-magic), almost unlimited settings as you can always add more planets to any system, and an atmosphere that can literally go from wild-west drama to Starship Trooper-style action to darkened horror within minutes. Â It's a game where you can essentially add huge amounts of lateral growth for all the races, have a metric ton of enemies to fight (it's space, after all), and balance the game in faction-specific performance rather than having to give everyone access to the same stuff.
The problems? Â They're a little harder to come up with... sometimes I think Blizz is creating a new sci-fi IP for Titan simply because a Starcraft MMORPG was almost too obvious of a good idea. Â I do see that there might be issues with it, though. Â As an IP, it's known, but it doesn't have the breadth that Azeroth's game universe had. Â Three-way faction balance on factions that operate in completely different ways might be exceptionally difficult (or not, depending). Â It might also simply be that Starcraft is only really going through it's second phase of serial development and maybe they wouldn't have wanted to really work on that idea until it was done. Â I'm not sure, but it mostly seems like Blizz looked at it and said, "You know what? Â It's too easy..."