... if jonathanh is right about why MS'ers don't post here -- because they don't want to deal with the supposed FUD being spread around -- or probably the sometimes negativity, I say, MS'ers, you guys gotta get thicker skins. Get some from Scoble.
I think there may some truth to the "MS employees are tired of dealing with the negativity" but IMHO there's a simpler answer.
My gut feel is that C9 has broad but shallow visibility at MS among the rank-and-file product team employees, and next to none in many job categories. Lots of people have heard of it, fewer have visited it, even fewer have re-visited it with any sort of frequency,
and nearly zero are going to spend their Sunday evening posting on the Coffeehouse forum.
If the C9 people did a classic product awareness type survey internally, asking devs, PMs, and testers about C9, I believe they would find that to be true.
Further, MS employees are really good at looking at things from an ROI perspective. "If I invest my limited time on C9, what is the return for me?"
It's really difficult for many people to see the benefit of spending time here (or elsewhere, like Slashdot) debating issues.