Some bloggy thing readers have said that this blog site won't let them sign their names if they don't have an account. While that's true for the automatic signatures that appears at the top of comments, there's nothing stopping you from signing your name in the body of the comment. I just ran a test and that works just fine.
Not signing your name doesn't automatically mean I won't approve your comment. However, if you're an anonymous troll or even a run-of-the-mill jerk who's proud to sign his name to his or her comments, odds are your comment will not be approved.
I prefer when posters sign their names. But it's not a deal-breaker in and of itself.