Personally, I find it a bit odd that gender-locking is even a thing when it comes to mogstation items. To me, it seems natural that you'd want your items to have the widest appeal in order to maximize sales. Having items that are wearable by both genders simply casts a wider net. Would it take some extra work? Maybe. I don't know this game's innards well enough to say... but I do imagine it'd help them sell more Y'shtola robes if more people could wear em.