> Then they complain a few years later when the UI they complained about and ultimately adopted gets changed again.

1) A few years later and you (or at least I) can't remember what the previous UI looked like. So if I don't complain about the change, it's only because I don't remember enough to recall what it used to be.

2) Exception: Windows 8. Nobody complained when Windows 9 came out, because they remembered what Windows 7 looked like (indeed, many of us were still using 7). (Of course some did complain that 9 didn't look exactly like 7, but since 9 was such an improvement over 8, their voices were muted.)