There is that, but part of me likes the idea of Esper form Terra being the only one with the required level of magical ability to use the really big spells. I mean, by the end pretty much anyone is more powerful than every Esper ever. Even the meat head who strayed from his gym. I'll admit I like that a bit more for story reasons than just for gameplay though. It just kind of gives me a warm and fuzzy feeling about it.