That way, you have the ability to learn multiple monster spells and can use them without making or breaking the game. The only task that the dev team would be pressed for is adding in a system that re-uses the abilities the monsters already use but putting in on our characters. The game would still be balanced bc you'd aleady be limited to certain number of base abilities, so you wouldn't have the whole, "you have to have this setup of spells for blu or we don't want you in our raid" and can still keep the full feel of blue mage. The other issue I saw was the learning curve...well you don't have to make it next to impossible to learn the spells out in the world bc it will be for glamour purposes. So a fresh lvl60 blue mage can still be just as strong as a vet lvl60 blue mage, just the vet would have these awesome looking spells, i.e. thunderbolt(behemoth).