Ironically, this attitude is a major blocker for the GIMP team when it comes to bigger UI/UX changes -- there's a vocal contingent who will react negatively to any change that requires a little adjustment to workflow or muscle memory, or even if things just look different.
Firefox's incredibly light-touch visual changes recently are a great example of this; it's not "this is demonstrably worse," it's "change makes me uncomfortable."
I do totally appreciate that changes can be genuinely problematic for a subset of users, especially the elderly, but the vitriol that gets spewed when a project overhauls a UI embarrasses me as a user.
Side note: the GIMP UI is generally pretty good these days. There's room for improvement, and it has a learning curve (as do all complex applications, to some degree) but it's shed a lot of its least intuitive aspects.