Right, because undocumented code is so valuable and useful.
In other words, no, I don't believe that "Open source is about writing code, first and foremost." Software development is more than just writing code. It's planning, testing, debugging, getting feedback from users, improving and maintaining it. Graphical apps need good artwork. Games need great artwork, music, and sound effects.
Amateurs dash off first drafts and then move on, leaving someone else to clean up the mess. Professionals recognize that good programming is a complex discipline with a lot of important inter-dependent roles.
OTOH, I do agree that encouraging more people to try programming is a good thing. I'm just not real crazy about this whole goofy hero-worship of coders.