Comments and dialogues
As Author writes, you don't strictly speaking need to have blog comments in order to have a (blog) dialog. Well, sort of (at least in my opinion). One of the strong advantages of blog comments, and I think why would-be commentators keep asking for them, is that they are the easiest way to make sure that the person who wrote the original entry sees your reaction to their entry. Fairly often the primary audience for your reaction is the original author, so not getting their attention renders your entire effort pointless.
(They can ignore your comment or pretend that it doesn't exist, for example by deleting it, but usually even this means that they've seen it. And yes, comments don't always guarantee that your reaction is seen, but I think that they are a lot more sure than the alternatives in practice.)
In practice I think it's somewhat more than that. Comments (at least comments that don't get moderated or deleted) offer a winning combination of being public, attracting the attention of the original author, and being the most likely way to get other people who read the original entry to see your reaction. Nothing else really comes close; email is private, and your own blog entry may not attract the attention of either the original author or other readers, especially if your blog is less widely read and influential.
(Given that people are social, I think that having an audience is important to people. Writing into the void is much less motivating. Also, at some level I think that it is impossible to have an actual dialog without attracting the other party's attention; otherwise you just have a bare reaction. I do think that you can have a dialog with the overall audience without the participation of the original author, though.)
What this suggests to me is that blogging needs better ways for people to discover and track such cross-blog references. In the specific case of the anime blogging community, my impression is that it is still small enough that someone could build a manually maintained 'planet anime' that pulled blog feeds in order to automatically discover such cross-references and assemble them for people to peruse. You'd probably want to structure things so that people could follow references both to specific blogs and to specific postings (ideally with syndication feeds for everything).
(Ignoring the censorship issue, trackbacks offer the possibility of achieving this without having to put your reaction in a comment, but they've been killed by spam. Things like Technorati searches might also do it, if they worked, but unfortunately they don't, at least not reliably.)
(I touched on this overall idea in passing in an earlier entry.)