It's pretty ridiculous for melee types to wear bikini metal - unless theyre a berserker type - but I think it makes a lot of sense for casters AS AN OPTION. Mages are sensitive, intuitive, and I think it's realistic for female mages to potentially prefer more revealing clothing. It can be a reflection of their artistic mind. I could completely believe a female mage evoking their artistic beauty by choosing to reveal more of their bodies.
Typically. male bodies are just not as artistically beautiful - powerful and attractive in different ways, but not really in a natural physical form sense. Of course, there could be half-naked male mages too, though Id guess any of them which chose that would end up celebrating a more feminine quality of beauty within themselves.
Soo - I think it makes sense for magic users, berserkers, or pretty unique and skilled assassin types! Even still, though, it'd be quite a statement of character. Which SHOULD have a place!
