have to be encouraged to take on the hard core, high value, high reputation roles.

Howeer, over the lifetime of a project, non-code contributions become very important. PostgreSQL, for example, has a very strict policy about including documentation with patches. In a presentation about how to contribute, Josh Berkus listed 50 ways, only five of which were code.

I think the perspective on what constitutes an open source project has shifted (some might say "matured" :) in the last ten years from "just the code" to the whole lifecycle of design, documentation, implementation and support.