Sorry Robert, if people have to create and log into their own blogs just to leave comments on other blogs they are reading... you'll lose at least 90% of the feedback. The barrier to entry is just to high. I have to:
1. Read your post
2. Create a blog if I don't have one. (The 90% case)
3. Open a new window to my blog
4. Cut and paste a link from your blog to mine... or at least somehow effectively reference your blog.
5. Post my entry
Compare this to two steps required to post a comment on most blogs that support comments effectively.
1. Read the blog.
2. Stay on the same page and post a comment.
I guess the basic problem is that not everyone in the world has a blog... nor does everyone want one. But I DO want to get feedback from people who don't blog. I do want to engage them in a conversation.
Sure, the five steps don't seem that complicated, but take a listen to what the social computer users of tomorrow, bloggers of last year (not of this year :-) ), and easily distracted/discouraged from technology teenagers from the Social Computing Symposium had to say.
Two steps is too much of a barrier to entry for most people today to leave comments. Why complicate things by requiring that we all have blogs? I know there will be more than a few people that disagree with me on this one... but blogging without a comment Field is not blogging to engage in a conversation. Want to know who a bad blogger is... ones that restrict comments to only other bloggers. :-)