It's a dead end for dedicated gamers, perhaps; it seems rife with gimmickry. But it seems to retain its appeal to the casual gamer, and really, that's what it was crapped out to do. What I hate is seeing it shoehorned into games that do not need it or benefit from it. I mean, it's cool to be able to free-form generate magic spells in a motion-controlled Fable game, but who gives a shit? Gimmickry. Or that Star Wars Kinect game. EAT MY SHIT.
Maybe it's a dead end, because casual gamers don't often see the need to rush out and buy Dance Central 2 when they already got Dance Central 1. I dunno. Seems like a short term type of plan to me, and they keep trying to shove motion control gaming down the throats of dedicated gamers. But casual gamers...they are fairly easy to seduce with gimmickry.
Actually Dance Party is a huge seller (I know you said Dance Central).
There are some aspects to motion gaming that work very well to me. Some of the pointing to select type of gestures. In Mario Kart, to to s roll with a kart, the flick is pretty nice.
I do agree though, if you have a quota of some sort, on what to shoehorn in, it almost always makes for bad gaming.