So you wanna start a search engine? Go ahead....make my day. How about a new operating system? You got that covered? It's called "barrier to entry". At some point nobody has the bucks to get in anymore. We can stop that with one tiny field (some aspects yet to be determined).
You can't compare these things.
Making a new pool is not that hard, it's hard to attract miners.
In the end I hope we will have a good decentralized pool, free of p2pool's weaknesses. I have a few ideas and there's a thred with proposals to improve p2pool.
So that centralization won't be that pressing.