as their track record in court on patent and copyright litigation shows they lose a lot more than they win, and when they lose they payout more than they ever collect in winning. But it could be just a protection scheme of threats with menaces as you suggest may be the case.

The interesting thing is if the big game makers do move away from Windows and DirectX to Open Standards then a very big hole in the Microsoft activities to create vendor lock-in begins to form and threaten the MS intent along those lines.