I heard that another good use for Kinect are exercise "games", basically virtual gym trainers. The thing has it's uses, just not for mainstream gaming. It's the same as with most controllers, really. When was the last time you used a joystick in anything else than a flight game (a dying genre, BTW)? Kinect is recent, so there are few games made for it, and the genres where it can shine simply haven't developed yet.
Also, my dad has an example of even more bizzare and "useless" controller. It's a gizmo which you put on three of your fingers, and which monitors your pulse (among other things). It's essentially a meditation aid, but he's got at least one game where it's used. The gameplay is unusual, to say the least. For example, there's a place where you have to shot an arrow at something, and you have to generally calm down to get a steady aim. I suspect that this kind of games, along with sports ones, could also exploit Kinect to it's full potential (in fact, combining this pulse control device with a light gun and Kinect could produce an excellent sport shooting trainer).