It frankly doesn't bother me one whit. Not for historical reasons, nor for "It seems as if" reasons, but for game design reasons.
Mages in MMOs are powerful. They have very strong ranged damage dealing (hello Black Mage!) or healing powers that allows them to play with devastating effect. Tanks, on the other hand, largely focus on being able to soak damage, and their use of heavy armor with it's powerful damage mitigation compliments this. For the same reason that White Mages have crap damage dealing abilities (to avoid the "I can do it all, hahahaha!" syndrome), mages in this game (and most MMOs) are limited in the armor they can use. High damage/heals at range? That's powerful. Counter it by making them fragile? That balances them against the other classes. If your Black Mage could wear Dragoon's armor and do Dragoon-levels of damage from anywhere on the map without worrying about positioning or being hit by the AOEs around a monster, why would anyone play a Dragoon? If a White Mage could clank around in Paladin's armor and simply keep aggro with their massive self-heal while letting the damage mitigation of the armor keep the incoming damage low enough to let them live, why would anyone play a Paladin or Warrior?
That's why RPGs and MMOs handwave odd restrictions like this. Not because they think that's the way it actually would be, but because they have to balance the game so that it's fun for everyone. The current setup, while not perfect, provides a solid mechanic that relies on well-balanced parties with well-balanced roles in order to succeed at the tougher content.
Mages in MMOs are powerful. They have very strong ranged damage dealing (hello Black Mage!) or healing powers that allows them to play with devastating effect. Tanks, on the other hand, largely focus on being able to soak damage, and their use of heavy armor with it's powerful damage mitigation compliments this. For the same reason that White Mages have crap damage dealing abilities (to avoid the "I can do it all, hahahaha!" syndrome), mages in this game (and most MMOs) are limited in the armor they can use. High damage/heals at range? That's powerful. Counter it by making them fragile? That balances them against the other classes. If your Black Mage could wear Dragoon's armor and do Dragoon-levels of damage from anywhere on the map without worrying about positioning or being hit by the AOEs around a monster, why would anyone play a Dragoon? If a White Mage could clank around in Paladin's armor and simply keep aggro with their massive self-heal while letting the damage mitigation of the armor keep the incoming damage low enough to let them live, why would anyone play a Paladin or Warrior?
That's why RPGs and MMOs handwave odd restrictions like this. Not because they think that's the way it actually would be, but because they have to balance the game so that it's fun for everyone. The current setup, while not perfect, provides a solid mechanic that relies on well-balanced parties with well-balanced roles in order to succeed at the tougher content.
