Some games just need interface. No one is going to pick a driving game where you hold nothing over one where you hold a wheel, or a sword game where you swing a sword over one where you swing an empty fist. Much less an air guitar over a Rock Band Beatles set.
Also, I dunno how well you guys could see that monitor when they were showing off the avatar controls , but it clearly has difficulty (at the moment) reading finite movement. While it can certainly see large full-body motions, the exact tilt, direction, and location of your hands and feet is not recognized well by this camera. There was also noticeable time delay between the girl's actions and the game's responses to those actions (somewhere between .25 and .5 seconds. Grossly unacceptable). If they really want you to play games using your fists, then finite controls like say holding a gun or swinging a sword would be significantly less accurate than even the Wiimote without motion plus.
There are absolutely some great uses for this in the future, but it is by default far more limited than something that combines motion controls and a human interface, rather than something that just eliminates the human interface altogether. I mean god, people complained about the lack of the second joystick on a Wiimote and the lack of buttons as limiting games. Think about how much this limits them.
