People generally are resistant to change. Especially if nothing is wrong with the current version of something, or if the “improvement” doesn’t seem to have any noticeable improved qualities. The main one that springs to mind is Facebook. Why on earth would they change it? There wasn’t a problem with it before. I can’t really put my finger on what it is about the new version that I don’t like, I just know that I didn’t have a problem with the old version, and the new one doesn’t seem like an improvement.
Feel free to mention any other examples, or explain why it happens, if anyone knows.