Don't Forget About Trade Secrets (Score 2)

There is an important point that you miss. Besides the difficulty of enforcing Copyrights on Software, which provides a motivation to not release source code. Microsoft almost assuredly considers its implementation the Windows OS to be a trade secret. And in order to keep trade secret status for their implementation they have to keep it a secret. Whatever your feelings of the Company or their products they do have a right to protect their IP, which they have spent huge amounts of money developing.

Chris Dickens