Imma spill some glamour option tea a bit...

[Iscah]

Also quick note to people asking why gender locking on outfits, I think honestly it is in part because the devs would have to spend more time, money, and effort adapting the clothes for male and female models, which they do for most glamours. Probably it’s as simple as they spent their resources doing other stuff.

This is the key to it, I think.

They're not simply averse to giving male characters any kind of "feminine" gear. They can use floral hairpins and an assortment of skirts.

What they do seem to avoid is chest pieces, which need more modelling work to be refitted for different body shapes. (And come to think of it, I think male characters have a wider range of body shapes than female characters do, which might add even more to the amount of relative work.)

Combined with the fact that only a relatively small portion of the playerbase will actually want to put those dresses on their male character, it's understandable that they'll consider it not worth their resources - unless there's high demand for it like the bunny suits. (Which I'm fairly sure got "lost in translation" on the way to that final result of an exact replica of the female version.)

Skirts wouldn't need the same kind of work - just stick the same 'tube' of the skirt onto the base model of each character's legs - and of course hats and jewellery are one-size-fits-all.

There are a few things they probably could selectively unlock because they have the models - eg. the Spring Dress specifically for male Highlanders, courtesy of Hildibrand, and the Riviera Vest for females since it was modelled for the Vampire's Vest item (and the non-vampire version has appeared on at least one NPC!) - but maybe it seems too messy to have individual exceptions like this.