This seems very simple: you buy something, you do as you please with it. It's called freedom. This is a minor and commercial manifestation of freedom, but it still is freedom.
This freedom is exactly what the RIAA, MPOA, and Microsoft want to take away from you. Leaving Microsoft aside for a moment, when was the last time Hollywood did anything that promoted our Founders' values in the Constitution? Is there any suprise to find them in a direct frontal assault on our freedom?
Once these organizations make it so your computer snitches on your for using music or movies in ways they do not approve of, it will be a short step to getting your computer to rat you out for any unapproved thought or activity.