I partly agree with you, but a few points..
1. The HP robes are BLACK and Universal is located in Florida, so maybe those aren't ideal. Though I suppose plenty of women endure the wearing of long back robes in the summer in places that are plenty hot.
2. In a certain context, don't we all dress up every day? I mean why does anyone bother with make up, dress shoes, high heels, suits, t-shirts? All our clothing choices make a statement of one kind or another.
3. Where I'd maybe say the costumes get a bit silly is when people pay $200+ for what is essentially just a flashlight, or any other situation where folks pay WAY too much for something like a pocketbook- just because it has a logo, or a picture of a certain rodent.
In a way, it doesn't impact me, any more than the woman wearing a nun's habit, or a hijab impacts me.
Unless....
Women are forced to wear a corset, bra, hijab. Or we assume all men are incapable of doing wrong, just because they are wearing a suit.
Or we give pretty people a higher salary.
Or a better loan rate.
Or maybe we can't share a water fountain, or public area because of what they are wearing.
Or...well, what if we wore nothing at all in WDW?