People don't hate changes, they hate learning new things. Most of them are lazy, and don't want to change their habits, no matter how bad they are. I know from my experience, that most valuable users will contact you directly (e-mail, support, twitter, other way) to describe their experiences before and after the change, telling you what exactly hurts them. Rest of them are pointless trolls with "First Comment Rule".…
Changes often don't solve anything of significance, just reshuffle stuff to be different or to be "cool". When you deal with dozens of apps and applications a day, having to relearn a UI is an annoyance.
Take the MS-Office "ribbon" change. Perhaps it may improve newbie learning a rough guess of 15%, but those of us who got used to the existing tool-bar by rote memorization were slowed for a few months. The ribbon changed one arbitrariness for another arbitrariness from our perspective. I can point out several irrationalities in the ribbon.