I think the problem is not volunteers: if a project has continous work and admins partecipate to forums, there is a lot of volunteers in the world. The problem is on researchers, Boinc have to attract scientists. And there are a lot of things to do: clear and costantly updated documentation (some parts of boinc site are older than 10 years), encourage the use of wrapper, etc. Have a ready-to-go boinc platform is important for new projects.