When I first started photoblogging, I spent hours commenting on other photoblogs, and got quite a few comments in return. Before long, though, it became a chore. I began to lose the initiative to post another image, just because I'd feel obligated to comment on many other sites.
That's wasn't why I started photoblogging. So I cut my list of sites down to a dozen or so favorites, and these people became my friends. I still post regularly, and many people still visit my sites, but I'm not as concerned about tons of comments anymore.
Of course, I still enjoy the comments I get. Everybody does. I still like seeing visits to my site increase in my stats, too.
But I've found that constructive criticism from random people isn't as helpful as you'd think. Everybody learns a different way to do things, everybody has their own style, and everybody has things they like more than others.
If you really want to learn and improve, join a photo club. Take some classes. Read some books. Shoot images that make YOU happy.
Isn't that why you starting taking photos?