The Photoshop thing, on the other hand, on the rare occasions I am forced to venture there, strikes me as a confusing mess that I'm always happy to leave behind as soon as possible. Plus of course it requires one kind or another of strange proprietary OS in order to function.

Honestly, they'd probably have to spin it off into a separate, UI-focused project that starts with minimal features and gradually adds more every time a good UI solution is found. In the order of what real-world users identify as the most needed features.

In other words, I believe what GIMP needs is a partnership with an idealistic professional workplace willing to use it as an experiment and communicate their day to day issues.

So you're surprised it's hard to find UI designers willing to work for free? I'd argue the surprising part is that there are programmers that ARE willing to work for free or reduced rates on open source.

Both of these disciplines take time and effort to learn and then perform. The people that do them not only pay these costs, but have their own obligations to themselves and their loved ones they might need to help support. It doesn't surprise me at all that the vast majority of people with these skills choose (or are forced by circumstance) to do something else.