Well I think thats natural. If I'm a developer, I would be cautious as well. I would rather stick to what I am good at, something that's proven to work and sell well.
I still feel that at the end of the day, only certain games are suitable to motion control. And the Wii controller just doesn't work well for more mainstream stuff. Even though motion control isn't exactly a new technology, it's still less suited to most game applications than traditional hold-in-my-hand-and-push-buttons style controllers.
Now if someone would invent whatever game she's playing below - they'd be very rich
BTW - I personally have nothing against the Wii or the DS or Nintendo, and in fact I love my DS to bits for it's JRPG goodness, but I dunno what it is about Nintendo but the Wii + DS has the largest amount of shovelcrap games I've ever seen. I think it's mainly because Nintendo has the more family friendly image of the big 3?
EDIT: BAH MY ANIMATED GIF DID NOT UPLOAD