It should be a little bit of both. The manufacturer should have some ideas and tech demos for the new feature, and then users and developers find new ways of using it once they get their hands on it and start fiddling, they shouldn't limit themselves to what the manufacturer has come up with.I don't see the point in having a camera on a video game device. I think past experiences have shown that it was a gimmick that didn't have a real use.
The gameplay ideas need to come first. It shouldn't be let's add a camera and see what the developers can come with...
should be the other way round
What I would really like to see from a camera is head tracking used for motion parallax effects, provided they use it sparingly and not beat us over the head with it until it's dead and we're sick of it, like they do with every other new feature.