The other problem is the same problem that the Wii has - to a serious gamer, most genres of games just aren't any more fun with motion tracking than they are with a standard controller.
The only genres that really seem to benefit from motion tracking are sports games where you don't have to run around like bowling and golf, and dance games.
For all other games, the motion controls are more cumbersome to use and are less precise than a regular controller. Motion controls for eg FPS or driving games just make games more frustrating if you're used to a normal controller.
But for someone who's a casual gamer who's not going to spend more than 30 mins at a time on the console, ie not really into gaming, motion controls can be appealing.
- James