Nicely ask in the bug tracker about how a designer can help. Maybe start with a mock of what you want to change. I'm sure most open source developers will put in extra effort to help you because they value contributions from designers.
The bashing is truly amazing. Not only does it lack constructiveness (in most cases), but Gnome (I speak of Gnome here not to the exclusion of KDE. I just happen to be a Gnome user) is beautiful, and has been for years.
Thank you Gnome team, including designers, that created such a beautiful desktop experience for me.
Design is more than beauty. Design is functionality, how you use stuff. As long as I rather jump into a terminal than navigate through the UI, that's a fail in my book, and very few DE's on Linux pass this test.