At the moment the project is playing things a little *too* safe. This is probably why so many projects can rely on it and yet it doesn't quite fire up enough passion from developers. Most people want to be rockstars, not maintainers!
A few very rough ideas that might help (some are opinions that you may not agree with. Some I don't fully agree with! ;):
1) Make the core project a little *more* exclusive. Allow the developers to feel proud they are skilled enough to be part of the team rather than just another pair of "punching hands".
2) Some sort of very simple user package repo (similar to AUR, or even openbsd-wip ports). Somewhere that people can work on their packages in a public place that gets them tested and popular. As it stands it is very hard for outsiders to add / maintain / improve source debs.
3) A formal handbook (not a wiki like Arch. More like FreeBSD). I worry that people might feel they are wasting time learning things that aren't the defacto way of doing things. I.e they don't know if this is an undocumented feature, likely to change or not. This will help increase passion and justify time spent with the project.
4) This is controversial but I absolutely think Gnome 3 as the default target has skilled developers running for the hills. They don't want to deal with it, they don't want to support it. They might even suspect the project is running off track because of it.
So yes, I do feel the project does need a little more diversity *of thought* (I don't give a crap about skin colour or genital shape, that isn't going to solve software issues). It needs to become a little more opinionated and try to fire up technical interest rather than just support other projects that suck all the time and efforts from developers.