Mileena must have felt insecure about exposing that much of her "back side" because it looks like the original lines for her costume is there and the shorts aspect was added later.
My favorite is Sonya, minus her face. Not saying she's ugly, just saying her face doesn't say Sonya when I look at it. I wish they would have made some fake teeth for Mileena. Would have been funny as hell.
"Aw man this chick is so hot, I'm so glad this is a real chick and not that crazy Tarkatan stuff."
*Takes off her mask.*
"What!? Damn you Ed Boooooooon!"