Well. From my disastrous NaNo experience last year(in which I actually managed to get through 50000 words of utter crap, while ruining my wrist and causing great(probably irreparable) damage to my mental facilities), I found that people do the NaNo because it's fun to get together and participate in Write-a-thons. I can probably see where you're coming from, but seriously, we're speaking about tons of people who have just procrastinated for a really long time; perhaps they get motivated by the fact that there are dozens of other people writing crap(or really good novels, you never know) along with them. Also, it's an opportunity to meet tons of other writers- I know I met a few really awesome people last year when I joined AIM write-a-thons. I think I enjoyed the experience(and the fact that I could gloat over my typing skills). I don't think I'll be doing it again(because I realised last year that it took me quite a lot of strength to force myself to not edit and just write, and I don't think it's possible for me to do that again), but I do think it has a certain appeal.

=)