Right now Microsoft has a couple of Kinect bundles (with Kinect-related games) for around $300. They also have a couple of bundles with a bigger hard drive and regular games for about the same price, and a stand-alone console for $120 less. For someone to choose a Kinect bundle over the other options, they'd have to be interested in the Kinect, which supports my original point.

The economics of the various bundles may have been different in the past, but it's never really been a "get this as a free add-on" kind of thing. The Kinect is expensive hardware, and I'm sure most of the people who have it (perhaps not all) compromised on other options in order to get it.