Isn't cooperative mining a form of communism ?
Personnaly I gave this a thought and I think it's useless and much harder to do than one might think.
First I thought it was a problem if only a few nodes were capable of mining. Now I don't care anymore. Even if only one was mining all new bitcoins, I wouldn't care much. This node would do all the work recquired, and in the best way. Plus, anyone can take its place if it can hash more.