From near as I can tell, unless Sounnsy has a lore post hidden away some where that I haven't seen, there is actually no lore reason behind those being the Arcanist spells. In fact there is nothing in lore that states an arcanist cannot use aspected aether. They already in fact do in the form of their carbuncles. In lore what defines someone as an arcanist is that they manipulate aether through the use of aether conductive ink and arcane geometries. I believe the actual reason behind the spells available to them in game is actually simply nothing more than game play. SE already had a dps class and a heal class based off of elemental usage and needed something different. I also am of the opinion that the person who designed Arcanist/SMN had a thing for affliction warlocks in WoW. It's pretty much the same reason Conjurers only use three elements in the visible game, Game Play reasons. There is nothing actually stopping a conjurer from making use of all of the elements.
“...most people need to believe in something. There are a few who don't, but they're a bit unusual.â€Â
-The Redemption of Althalus
“Sparhawk grinned. "If Martel finds out that he's drinking again, he'll reach down his throat and pull his heart out."Â
"Can you actually do that to a man?"Â
"You can if your arm's long enough, and if you know what you're looking for.[...]â€Â
-The Diamond Throne
-The Redemption of Althalus
“Sparhawk grinned. "If Martel finds out that he's drinking again, he'll reach down his throat and pull his heart out."Â
"Can you actually do that to a man?"Â
"You can if your arm's long enough, and if you know what you're looking for.[...]â€Â
-The Diamond Throne
