Stryker is NOT Earth with fantasy elements. Sonya & Jax are. Stryker isn't. He doesn't belong.
On that note, I can say everyone that appeared after MK3 doesn't belong, because the story went completely berserk and weird at that point. There's nothing wrong with Stryker. He's the Batman of the MK world. He's gorgeous, certainly better looking than any other character in the game now (except maybe Nightwolf!).
I love the idea of a character without fantasy elements. It really brings immersion into the equation--it's not just a fighting game anymore, it's a story to be told.
Plus there's nothing more satisfying than wondering what the hell is going through, say, Quan Chi's mind as he's being pounded by a regular old beat cop.
Edit: Did I mention that Stryker gave me a cop fetish? :|