The thing is, it would probably do better on ps3 and 360 then it would wii. And yes it has to do with the audience. Whatever you think of the wii, you must admit it has a large amount of kids and older people who would not be interested in extraction. The HD systems have a built in dead space fan base and thus, while extraction wouldn't burn up the sales charts on any system, it would do better on them.
Time for hype