p2pool has some peculiarities that complicate things. In March I had to help Balthazar to fix p2pool related block chain fork in NVC. This requires a hard fork protocol change (https://github.com/sunnyking/novacoin/commit/002d24c658e4a2d8306cf69c62ac3c666d106f64
For PPC it is currently managed as critical public infrastructure, I don't intend to rush protocol changes unless it is absolutely necessary. Because ppc has proof-of-stake, decentralized mining network is not considered high priority. Even if all major ppc pools are under dos the impact is not severe to ppc network.
As to merged mining (introduced by namecoin), it is a common misunderstanding that merge-mining saves energy. What it does is strengthening parent network (bitcoin), not saving energy. This is because the energy is either consumed mining an altcoin not merge-mineable, or consumed mining bitcoin with merge-mining. So actually no energy is saved. In comparison proof-of-stake technology does save energy, by taking market share from pure proof-of-work networks.