Michelle Levesque contemplates about the role of Interface Design in Open Source Software:
The lack of focus on user interface design causes users to prefer proprietary software’s more intuitive interface. Open Source software tends to lack the complete and accessible documentation that retains users. Developers focus on features in their software, rather than ensuring that they have a solid core. (…) If Open Source software wishes to become widely used and embraced by the general public, all issues will have to be overcome.
I can only second this position. I have evaluated many open source projects and I am amazed that the User Interface Design is seen as a followup problem — if at all.
The animosity of software developers about interface design issues is steady. The problem here is not that they devalue the issue in general, but that there are common misconceptions about the importance. There is usually also minimal or no knowledge about how to ensure usable software at all in many open source projects.