This is a flaw of a decentralized currency powered by democracy. The following is a nice video on explaining the implications of this effect:

http://www.youtube.com/watch?v=s7tWHJfhiyo

In essence, those who are worrying about a single pool getting to 51% (i.e. "first past the post") will go to the second largest pool, instead to the smaller ones. Essentially only two pools will be left.

Same with the two-party system in America.