"Modification of its products" "Product tampering"

So if I write a linux device driver for a USB mouse with a proprietary interface, I am "tampering" with the mouse and "modifying" it?

This is a human interface device. I highly doubt that even the DCMA could kick in on it, since it is not used for recording, storing, or displaying content of any kind (but I could be wrong). How, then, does Microsoft have the right to say what can and cannot be done with a piece of hardware that I rightfully purchased?

Whether the Kinect is a loss leader is irrelevant. Once I buy the thing, I own it, and I can do whatever I want to with it.