I learned 10+ years ago that deleting comments was a bad idea. Obviously, spam, scams, hate, porn and malware should be deleted, but real comments (critical or otherwise), voicing real concerns, by real people shouldn't be deleted. In fact, there's a long internal discussion going on here at ZDNet about how to better manage the spam trickling into the TalkBacks. (For now, keep flagging them...)
I was going to end this post by saying that despite TUAW's story, there were still some posts about the bad Consumer Reports review of the iPhone 4 in the Apple forums -- there were some there this morning -- but alas, they also appear to have been deleted, so I can't.
Maybe if Apple spent as much time fixing the iPhone 4 flaws as it did deleting critical comments we'd actually see a software update for the iLemon in a timely manner.
(At least fix the silly proximity sensor bug so that I can actually make a phone call without hanging up every time!)