Think about how many great discussions there are here, or in the best threads on Slashdot, Reddit, and plenty of other places. So it seems to me there are plenty of great comments that help people think, learn, grow, etc. True, there are plenty of comments that aren't so great ... so one way to look at "reinventing comments" is to how to magnify what's good and minimize the "get you angry" factor and other downsides.