The only thing I'm particularly partial to would be letting Artifact Armor remain job-locked. Part of me wouldn't mind the freedom to mix and match, since I love some of the sets but don't play the job, but it's the one area where it's a decision to keep something so intertwined with job-identity that it doesn't bother me.

For everything else, I'd rather the freedom to mix and match. Even from a realism point of view, the vast majority of the cultures on Eorzea have extended contact/trade/exchange of ideas to where it wouldn't really be that out there to see a sharing of attire/designs/patterns/styles etc... amongst each other. But, even then, from a realism point of view: there's talking dragons in this game, and we can wear jeans and a t-shirt with shades and drive a car.

That said, I don't think anything should be genderlocked at this point; including hairstyles/makeup options and the like. Ultimately, the locks are arbitrary and it really doesn't matter if [Female Character] wears a traditionally masculine set of attire, or vice-versa.