Interesting idea, but the barrier of entry to contribute code to a complex project like Blender is waaaaaaaaay higher than the artists there seem to imagine.
As for the interface - I find it dire for detailed editing tasks(I opt to use Wings for modelling) but not too bad for managing the overall scene, applying materials, lighting, compositing, etc. I speak as someone who's invested a bare minimum of time into properly learning to use it.
Your right about how clean/responsive and fast it is. They have justifiable pride in how many features they include in such a small binary. When I was hacking on it Blender weighed in at under 10 megabytes with features other apps needed 100s of megabytes to provide. I think they still come in under 20 but I haven't checked in a while.
(But Wings is still a better modeller.)
I'm not saying it's easy or requires any less talent than coding - just that it doesn't have as many "prerequisites" as modifying Blender would.