The argument SE made about it is so silly because Blm *can* wear armor in a dungeon: the pvp sets. (Fierce Tyrant, etc).
And tanks can wear bikini's or 2B's outfit. So that argument holds absolutely zero weight.
And my healer can be a clown or a chicken suit.
It's not like SE was going for realism or immersion when they make all those joke outfits, so why try to claim it suddenly in defense of why they can't/won't unlock outfits?

Let us wear what we want to wear. Having the ability to mix and match pieces would open up whole new worlds with glamours.
Could easily make it that if you pick up the piece in a dungeon, it is job locked until it is put in the dresser. Once in the dresser, it becomes freely usable since all it is in there is a glamour anyway and stats don't matter. (Granted, I'd also like the 'once you pick up the piece once, it unlocks it in a book for you' so you could in theory have everything available instead of a limited slot amounts, but alas)