While all bloggers like new followers and increased stats, I think most bloggers LOVE comments. Comments show that a blog has active readers, that not only take the time to read posts, but also to share their own thoughts. Importantly, comments also allow bloggers to get to know their readers.
I also believe, however, that comments are also one of the hardest things to receive. I know this from my personal experience. To elaborate (Warning, this might get boring. Feel free to skip to the next paragraph.), I use google reader to update my blog. I go through my unread items and star the ones that I want to read later. When I read my starred items, I'll comment on particularly striking posts. Here's where the problem comes. A lot of times, I'll star items, and then I'll star even more items. Before I know it, I'll have hundreds of items I need to read. There's no way I can read all those items, so I usually just unstar them, and start over from my unread items. I wish I could say that I'll make sure my starred items do not pile up, but I know that life is busy. But I also know that comments make an IMPACT.
In short, I think readers have good intentions, and may genuinely like certain blogs, but simply do not have time to comment and read many entries. Also, the large number of great blogs also makes it difficult to comment. At the same time, most bloggers spend hours writing posts for their readers, so to know that readers appreciate them is great. Appreciation also helps bloggers find the motivation to improve their blogs, so shouldn't readers try to comment more, even if it is just a little?
So here's my pledge to comment more on my favorite blogs, and I hope you do the same. :)