Materia all the things!

All gear should be purely cosmetic and crafted only but with NO STATS. Then instead, quest/raid rewards and drops are materia - so for your AF quests you have to go and find materia that has the same stats as the AF currently in play, which you can then meld to whatever the hell you think looks the coolest, though restricted by class/job.

Standard materia would take one slot on a piece, materia dropped from primals would take four slots. Hopefully that wouldn't cause an imbalance and would mean you could wear clown shoes if you wanted (and if they were in the game).