I think a lot of people don't like the direction MS has been taking in the last 18-24 months or so. That is a big source of complaints and rightfully so. If no-one complains, MS might actually think they are doing the right thing.
Although I agree this isn't the forum for MS feedback but since this forum is supposed to be about MS related technologies, I think you can't help but have it spill over here.
Having constructive feedback is not the same as being negative.
Being negative is saying "Windows 8 sucks". Being constructive is saying "What are the changes in Windows 8, and what were the reasons those changes were made?". Once (and only once) you understand why the changes were made, you can come to a better discussion about whether the parameters are sound (does everyone have a touch screen?) and if they are, whether Microsoft's approach given those parameters is sound.
One of the things that I find so cool about C9 is the fact that when they talk to the developers, there's usually a really good reason behind decisions that you disagree with that surprise you because they come from a completely different direction.
For example: "Gosh, Win8 sucks because I can't get into BIOS without first going into Windows. What a PITA", followed by the video (http://channel9.msdn.com/Shows/Going+Deep/Inside-Windows-8-Chris-Stevens-Boot-Environment) leaving you saying "Oh, I had completely not thought that getting the keyboard active takes seconds on the boot process, and doing this in the BIOS rather than in parallel with other Windows drivers booting slows my boot process down by an average of 2-4 seconds". Given that constraint, suddenly I feel less bad about Windows doing it in the way it is doing it.
This is why I hate all of the negativity on C9. C9 to me isn't a good place to complain that Microsoft did X, but is a totally awesome place for finding out why they made it the way they did.
Complaining is boring and easy. Understanding is harder, but it's more fun too (as any good developer should know).
That's not to say that Microsoft are always right (they often aren't). But complaining about Microsoft on C9 seems to me to just miss the potential and the awesomeness of C9. It's like going to a 5-star Michelin restaurant and complaining that the food sucks loudly in the restaurant It's fine if that happens a couple of times, people can get on with it. It's even better if a bunch of real foodies come in and discuss the food at a high level - the chefs would love that.,
But if too many people start to complain loudly, and it becomes almost "acceptable" or "normal" for everyone to say "nom nom nom, this food is terrible. Gosh nom nom this chef is awful, yes, waiter, more please nom nom" then you shouldn't be surprised that the chefs get fed up, close the restaurant and go home.
C9 is a rare luxury. Apple has nowhere on the web quite as deep and technical as C9. Google has nowhere as awesome as C9. Microsoft only has C9. Don't screw it up by complaining too loud in their restaurant. If you don't like it, you're always free to go elsewhere.