Developer Preview and Consumer Preview had the biggest userbase of any beta ever before in history for any technology product ever.
Now there's an argument about whether they did anything with the feedback, but claiming that they didn't collect it is just utter, fact-ignoring bokum.
The didn't listen about any of the UI issues and design decisions. It was just there to iron out the bugs, but the GUI (the main "bug" of W8) was never up for a honest test with the preview versions.
It went like this:
user 1: Hi there! I like Windows 8.
user 2: You said Aero shouldn't be in Windows 8 because it harms battery life, but that doesn't make sense because Aero can be turned off when the computer is on battery. It actually wasn't long ago that Microsoft was defending Aero as having minimal impact on battery life. Are you now going to claim that Microsoft was wrong? In fact I have multiple links showing specific benchmarks that Aero only uses 1-4% when on and.....
user 3: Will Windows 8 have a Twitter app?
Sinofsky: That's a great question that I'd be happy to answer. Yes Windows 8 will have a Twitter pp.
(week later user 2 comment is gone)
I was there on the W8 blog, it was exactly like that.