I like magic and skill growth to be tied to levels because it makes leveling more interesting to me and I also like that you can become super powerful early in FFIV if you so choose without being limited only to the spells available at a specific point in the game. You can learn Meteo as soon as you get a magic caster if you're masochistic enough to grins that much.

I also tend to feel FFVI makes it less satisfying due to diminishing returns. It just kind of becomes rote that everyone is casting magic later in the game. So yeah, it's OP, but the combination of being OP and everyone has access to it actually makes it less satisfying to me.