Every industry has this problem that lead to market concentration. Big pools get smaller costs by miner, thus offering lower fees and then getting more miners. Same with any other industry (eg amazon, nike, walmart, bp, you name it). I guess the only option would be like a p2pool, a protocol level designed pool, with no admin that would offer 0 fees. However it may be harder to implement specific high speed communications between miners to work with coordination. Clearly big pools use their own specific custom made super fast protocols so they save time on gossip, proof sending, block building, etc. IMHO.