The whole concept of changing your clothing mid-battle is ridiculous though. Even in other games it's completely out of the question.

If I'm fighting a Rathalos in Monster Hunter I can't just say "Hold on, I need to switch to my status effect + gear to use these throwing knives, then back to my element attack + gear to start fighting you with my sword again!" I plan ahead and use what I think is best for that fight. You can't do everything, go with what you think is most effective.

Even still as far as MMOs as a whole go you don't see other games allowing you to switch gear mid-battle outside of FFXI. Most suffer from the "1 optimal set" problem but that has nothing to do with switching mid-battle.

Allowing people to switch mid-battle and operate all roles in a single battle goes back to the argument that all classes feel the same and even within the same class the roles are barely diversified. If you have to plan out your gear beforehand with no mid-battle swaps then at least you may have different people playing different roles. Isn't that what everyone wanted? More class/role diversification and not allowing everyone to do everything?