It's not nice to care about people unfollowing you. Twitter is used by many as a stream of news, so it's a natural process that my interests shifts over time I want to unfollow people twitting about stuff that are no longer pertinent to what I'm doing right now.
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.
