I believe that any rational criticism is constructive in the sense that an argument against something is an argument for something else (creative destruction).
That said, there are people whose purpose in life appear to orbit negatively-charged criticism (as good as-) 100% of the time. I like a good solid rant but there ought to be a counter-point, a passionate statement of positive bias once in a while from the same people. And this is a Microsoft forum, so it doesn't hurt if that positive bias is about something Microsoft-related -- otherwise why are you here anyway?
Don't spend all energy on what you don't like: pour energy into what you do like (at least in a technology context). There are some threads, but could be more, about topics that people are positively passionate about.
I positively enjoy the speculative threads by Felix. His threads are examples of enthusiasm. They don't dwell on negativity but focus on the positive future developments comming out of research (and development) teams.