The problem with design is that it is something that is not easy, but it SEEMS easy, because everyone has an opinion, and they think it's just as valid as anyone else's, even a professional designer. This isn't true. The people who designed the first 15 years of Linux interfaces should have never been allowed to design anything.
It's like the other guy said - if you optimized code and a designer came in and ripped out everything you did, rewrote it to be more "aesthetically pleasing", you would be pissed. If it happened twice, you'd throw a fit, and if it happened again you'd be done.
There needs to be a distinct process in place for contributing that doesn't include a programmer redesigning things before they get put into place. If the developer was competent to design, there would have been no need for the designer in the first place.