It would only be humiliating for insecure macho pricks. None of the male MK characters have shown any signs of sexism. If that kind of "finisher" wasn't treated as degrading, but just something done for fun, that'd be another story. I wouldn't mind seeing how certain of the men would look like as girls, and you should also be able to turn girls into men.

I'm certainly not an insecure person as was mentioned as a negative point but I don't think these would work too well, it just seems... for lack of a better word... ridiculous.
Having said that I like the creativity behind such an idea.

I think that one problem with the OP's idea is that he doesn't understand why Demitri turns men into women. It's because he prefers female victims, weak ones at that.

Why would it bother Scorpion, Sub-Zero or Kano to be turned into women? I'm sure some will immediatly assume Kano to be a sexist, homophobic piece of shit, but we've never seen him mock Sonya for being a gal, nor has he ever called any other men faggots. It's not because of political correctness (at least not just that), it's because Kano's personality doesn't require him to be a sexist, homophobic twat.

The ideia iis only for fun as a Friendship to finish... forget the sex of real world, it's only a new option of finish, any character will be rape.
It is so ridiculous as a babality... but is fun.
And we could see male characters if was females, we could see the girls as men too.
Shang Tsung transform himself in girl fighters... Who call him of gay or other thing? Anybody...
So, lets fun with this...

Ahhh Rule 63.

Actually that could be on of Quan Chi's -alities or Friendship, rather than give it to everyone.

It made sense for Demitri, as he is a male vampire who wants to suck blood from fair maidens. It would not make sense to put it in MK though. So I vote no.

This type of finisher could be used to reference certain characters if they didn't make it. For instance, Sonya could be turned into Kobra (or vice versa, but Kobra is unlikely not to be in the same game as Sonya now), Sub-Zero into Frost, Goro into Sheeva, Sheeva into one of the male Shokans, if either Goro or Kintaro weren't included, etc.

For Mileena, I was thinking of giving her a male Edenian body, with Baraka's head. I just have this picture in mind of Mileena's new male body, with Baraka's head, and the MK2 female ninja outfit.