People are lazy.

If it takes more effort for them to do something, then they’re not really going to do it. But if you want to encourage discussion, you don’t want to make it really hard for them to do it. You don’t want them to have to a) Register b) Verify their email c) Come back again and login. Blogs aren’t forums or message boards.

The fastest and most convenient way is 9 times out of 10 the best way. Let them fill in their name and email and their thoughts. If they cause you trouble, there’s always the banhammer. Bloggers ought to try to make their blogs as accessible as much as possible to facilitate discussion. But try it for yourself first. If you don’t agree or dislike it, you can easily turn on registration.