..which would basically mean NO COOLDOWN AT ALL for mages..and while that would make me extremely powerful, it would also take away any suspense and therefore fun.
I could be dishing out spells, heals and buffs like crazy and the only thing to worry about would be MP.
Now I have to be careful to have the AoE toggle on while buffing, because I'll have to wait a minute until I'm able to rebuff them, I have to think about an appropriate time to heal someone, because if I do it at the wrong moment and the player gets hit AFTER my heal, I can't heal him for several seconds, etc.
That's more interesting than just slamming buttons until my MP bar is empty.