@korbe: Ok, let me just rephrase it differently.
Nokia is not in the 'opensource business' solely for opensource's sake.
Surely they see this as an investment, an incubation project to grow an opensource OS that can be used on their products because they're not in the OS business. AND if you understand this part, then you'd see that going mainstream (and succeeding) is in the symbiotic interest of both the community and nokia. Unless, this niche can grow big enough, to be profitable enough to sustain the niche's dream.