Is there no interest in having a p2pool? I think it would be pretty cool to have something like this.
Why is there no P2Pool for miners?
Because no one has developed it yet.
Additionally, a 2 minute block time is very difficult to work with for a p2pool system. AFAIK, the p2pool system works because there are 30 second blocks in the p2ool sharechain, while there are 10 minute blocks in the bitcoin main chain. So, every 30 seconds there is an agreement amongst all the miners in the "pool" regarding how much work everyone has done.
So essentially, in monero, if the same p2pool architecture is used, there would need to be a secondary chain that is capable of reaching consensus in between the time when the real Monero chain reaches consensus.