[Nick Fury]

A: It's not illegal for them to do that. They write the EULAs and the users agree to 'em.

B: The corporate keys are a weird loop hole and they are probably the solution that will be used by piraters

C: Even if the corporate keys aren't used by piraters, MS still has to release security patches that can be downloaded and run without the "windows update" utility. This means that cracks and patches will be used by the pirates.

D: It means more viruses for MS to deal with and take blame for.... sucks for them.

EDIT: As proof of 'A' I suggest everyone actually sit down and READ the Windows XP EULA. It is quite a piece of work if I do say so myself. It is a legally binding license and MS has far more lawyers and legal power than a pirate so I'm fairly certain these issues have been addressed.