I think you're reading into too much, it's Mortal Kombat for fucks sake. You do understand the character was created around 1993, right? She's a clone of Kitana and was thought to be part-Nomad like Baraka, hence the bestial mouth. I guess they're changing the story some since this as a retelling though.
If anything, she's very much empowered... she's a killing machine. It would be fucked up and sexist if she was just made to shake her ass in the background as you fought. No, the women of Mortal Kombat and made to fuck people up hardcore as well as any of the male characters.
The outfit is arbitrary fan service to young males that need pointless artificial stimulation in their games. The essence of the character is very much what we real MK Fans expect of Mileena. To us, it doesn't matter what her costume looks like, we know what she's all about... and being dominated by the male characters via story line is not one of them. She serves Shao Kahn like any of his other cohorts. Shit, she's guaranteed to have an ending where she betrays him provided you have to fight him at the final stage.