Awww come on now! Look at the history of overpriced peripherals and how well they take off. I'm sure this one will do just as good as all the others have in the past. The SEGA CD was a huge success (don't look it up, just trust me) The 32x breathed new life (**cough**) into cartridge games. Sony's EyeToy (a.k.a. a freaking web cam) changed the world with it's "interactive, you're in the game" fun, at least Sony and the 15 people that bought it did.
overpriced peripherals do one thing, and one thing only. Fracture a market.
Is it sad to say I'm more excited to see what the hacking community comes up with once they've got drivers for the Kinect running on a PC.