I hope that those of you who request source code noticed that most of the time, after an emulation project goes open source (after repetitive requests from various people) it ends up dying up after having other stuff, unrelated to emulation added to it.
When PJ64 went open, no one grabbed the source to continue development.
When Mupen64 went open only a few did and the progress has been minor over all this time.
When Demul was open (it was, a long time ago) no person touched the code apart from the original staff.
The same happens to other projects too. Yabause, nullDC, PCSX2, PCSX, younameit. Even MAME (and similar projects) are kept updated due to the amount of work casual (older) project members do.
The only open emulation projects having lots of new active contributors are the ones for newer systems, like Dolphin and desmume (until emulators for even newer systems come out).