The point about piracy is a strong enough reason for freeing the source code. Why not just let people buy quality support instead of some blurb of binary data? It also would be interesting to see how many different forks emerge out of the original code base. A kind of fork comes to my mind is a specialized Windows build for high performance gaming. Gamers would be dedicated enough to build community support around their fork, then Microsoft can fight over a monopoly on "better support" instead.