Both male and female humans wear non gender specific garb - PANTS!
Are you even listening? The idea that pants are not gender-specific is an extremely recent one. Even as recently as the '70s, during my own lifetime, pants were considered masculine attire, and girls who wore pants were considered tomboys.
I noticed that point several posts ago, and I am unsure why you are bringing it into the discussion as it alone proves that Starfleet is a progressive organization by "current" standards. Even in the late 80's there were still lots of people who felt wearing pants was not a "womanly" thing to do, which was and is silly. So putting women in pants was a big sartorial step for the creators and writers. In addition, Counselor Troi was given a regular uniform which was a big step at the time when just a few years previously in the U.S. Army men and women had different uniforms. So pants = progress. What seems to be the issue is that now the "progressive" thing to do is to have males wear what has traditionally been considered female clothing, although such an idea ignores that men have been wearing flowing garments for a very long time.
So my contention is that the writers and creators of Star Trek have already shown that Starfleet is a progressive organization sartorially, and that inclusion of the skant won't change that. Therefore an author can choose to include the skant or not based on their opinion of the appearance of the skant itself and not be judged "sexist" if they decide not to have one of their male characters wear one.