Kinect is dead. Long live the Leap Motion
live.leapmotion.com
live.leapmotion.com
You can design an interface for just about any reasonable level of precision, but this appears to be a good match for the type of touch interfaces we're already seeing in iOS, Android, and Metro. Metro with a mouse kind of sucks, if I'm being honest. Metro with something like this would feel a lot more like direct manipulation, which is what touch UI delivers.
A couple of reasons that came to mind:
1) Smudges! I tolerate them on my touch devices, but they really annoy me. Gesture-based manipulation takes you three-quarters of the way to touch UI without the actual touching.
2) Gestures detection can occur in a plane that is different than the screen surface. A big reason we don't all use touch screens on our desks is because of the "gorilla arms" problem. Any interface that requires you to extend your arms to shoulder height must be limited to infrequent use because of fatigue. With a remote sensor like this, you wouldn't have to reach all the way to your screen.
You can see the benefits of this with a simple exercise. Reach forward at chest height to the point that your hand just barely passes the front edge of your keyboard and hold it for a 10 count. Now do the same exercise, but reach all the way to your screen. Hold that for a 10 count and the difference will become clear.