Maybe because there's too many users not wanting to jump ship due to love for proprietary SPen stuff.. That means unless a developer has the phone (not many of the great ones have) and wants to run aosp, there won't be much progress.
Guess you could be the first
I'm also so desperate after aosp that I've considered trying to learn and make a aosp rom, but it's a huge jump for someone who hasn't developed; Even temasek (great kanger) hasn't tried anything on his own, and he has both great skills and a n3.
Alas, guess the whole community is waiting for cm to make the first move, once it happens there'll probably be an onslaught of aosp roms for our device.
Omnirom would be my first priority
I guess we could ask around for good devs with the n3 and perhaps somebody would start, or buy/raise money for one for Pulser, or somebody else, on a good aosp team.