Lately I've been getting a lot of users registering to the site, but fewer and fewer comments. So I've become suspicious of these new user registrations as the only advantage to registering is that commenting becomes ever so slightly easier. That and the fact that a lot of the names just sound so spammy. So I've turned off the ability to register as a user of this site. Having the feature enabled has just been generating a lot of unwanted and unnecessary email for me, and is really not advantageous to anyone else, including spammers. In addition, I've pretty much disabled comment moderation, thus bringing the advantages to registering as a Subscriber down to a firm zero. My spam filter seems to be handling the spam plenty well, and the three or four people who ever leave comments here are very well behaved, so I don't anticipate any problems.
If, for some reason, I'm missing something about the user registration feature, and people are registering — or would like to register — for legitimate reasons, please let me know and I'll re-enable the feature.