In ancient scottland women were not allowed to wear kilts (even today it is not the correct form of dress). Women had their own specific garments, most of which were ankle length dresses.So in Scotland women should wear skirts, because men wear them. Got it.
It's not about the specific clothing, it's about the men dressing like men and the women dressing like women. That is much more difficult when the culture is trying to blend those two (men and women) together.
If a woman is wearing "women's" jeans and a baggy sweatshirt she probably could be mistaken for a young man. I doubt anyone here would promote "men's" dresses in a western society. And even the robes of the ancient middle east had gender specific components.
I have no problem with churches having dress codes. I just think they should be upfront about it and give their reasoning. I also don't think any church should be telling women what they should wear. If there is an issue with the woman's clothes her husband or father should be the one it is brought up with.