It's a sad state of affairs, but it is pretty common for the designer to just "push pixels" on engineer command - the engineer conceives (horribly) the UI in his head, sketches, and then tells the designer to make it pretty. The designer is merely a decorator. I saw it happen a lot in a telco, but it happens almost anywhere where the engineering skills are considered the core.
Feels to me that no designer worked on Gimp UX.
But good UX is about objectivity and about efficiency. Its also a process.
Another thing is that there is no tradition in that for designers. Opensource programming free time fun project for programmer is equivalent maybe something like making print posters for designers.
And interaction design schools are hardly helping that, they should make students to help out on opensource projects maybe as part of their assignments/diplomas.
How would i join opensource projects that need designers? I dont know.
I think it's because as a programmer my mental model more closely matches that of another programmer.
Which is terrifying when I do UX stuff myself because then I worry I'm building stuff for other programmers when I'm aiming at general users.
For example average user has mostly no understanding of things like reading data into memory and that it must be saved aferwards. For him the edit is already on the screen, like when you write on paper.
Also ux quality is imposible to measure. Lot of times its desicions between Ok bot not great vs Ok but not great.
The biggest problem on opensource projects is no consistent unifying philosophy, no aim. Users can learn anything, it just has to be consistent. Lot of times there is one developer wanting to see every posible function on the sceen, second one is making contextualy avare menus and thir one believes in text input search. Three of those together are just a mess.
The funny thing is, engineers actually understand this perfectly when talking about text processors, but for some reason they (we) often fail to generalise it to other fields.