Why is it disappointing?

Microsoft has become a company that produces technological advances as a side-effect of their primary goal, which is making money. They are not really interested in sharing, or promoting innovation - they are interested in generating lock-in, collecting licensing fees, and stamping out the competition.

What I find truly disappointing is that there are so many brilliant, creative people letting their work be owned and controlled by companies like Microsoft.

Open source projects get admiration and passion because they are OPEN. The top priority is to share the discovery or creation and promote productivity and innovation among others.