I think blog comments aren’t productive, that’s why I don’t allow them. A lot has been said, I’ll just quote what I agree with:

“…to the extent that comments interfere with the natural expression of the unedited voice of an individual, comments may act to make something not a blog…. The cool thing about blogs is that while they may be quiet, and it may be hard to find what you’re looking for, at least you can say what you think without being shouted down. This makes it possible for unpopular ideas to be expressed. And if you know history, the most important ideas often are the unpopular ones…. That’s what’s important about blogs, not that people can comment on your ideas. As long as they can start their own blog, there will be no shortage of places to comment.” Dave Winer ideas about comments on blogs.

[youtube]http://www.youtube.com/watch?v=vzgEi_u9-88[/youtube]

“The important thing to notice here is that Dave does not see blog comments as productive to the free exchange of ideas. They are a part of the problem, not the solution. You don’t have a right to post your thoughts at the bottom of someone else’s thoughts. That’s not freedom of expression, that’s an infringement on their freedom of expression. Get your own space, write compelling things, and if your ideas are smart, they’ll be linked to, and Google will notice, and you’ll move up in PageRank, and you’ll have influence and your ideas will have power.”

“When a blog allows comments right below the writer’s post, what you get is a bunch of interesting ideas, carefully constructed, followed by a long spew of noise, filth, and anonymous rubbish that nobody … nobody … would say out loud if they had to take ownership of their words. Look at this innocent post on a real estate blog. By comment #6 you’re already seeing complete noise. By #13 you have someone cursing and saying “go kill yourself.” On a real estate blog. #18 and #23 have launched into a middle eastern nuclear conflageration which continues for 100 posts.” Joel Spolsky