Coming from the single player FF games, its a natural way to think. You usually have a ton of ethers to get your mana back, and can spam your highest level spells in any important fight. In this game(for BLM at least) they changed the parameters of the spells in such a way that they have different ideal uses. Once youve wrapped your head around it you realize that theyve given you tools for more situations, just with a naming scheme that might leave something to be desired.