A couple of reasons. First of all, the UI is just a means to an end. If it changes just for the sake of re-arranging, then people have to put in more effort to

A couple of reasons. First of all, the UI is just a means to an end. If it changes just for the sake of re-arranging, then people have to put in more effort to accomplish the same thing they were doing before. Sure, most people will eventually adapt. But, still feels like a waste of time when the updates offer no real increase to functionality, and sometimes seem to reduce it. Secondly, the complaints come because, for many of us, our computers and phones feel like an extension of our offices and homes. We're staring at these screens for the majority of waking hours. The UI is basically part of the furniture. Many people would feel resentful if their chairs, couches, and doorknobs were changed without permission every year as part of some update. They're going to have similar feelings about the electronic portions of their spaces.