Fair enough - but "nice" has nothing to do with it. If you're using Twitter, as many are, to get a message out, it's useful to know who no longer thinks your message is interesting, especially if you can pair it with a cause (a recent tweet that may have been offensive or a string of self-centered tweets, e.g.).

Like I said, I was just tinkering around and thought I'd share something I made that might be useful to someone.