It seems to me that the problem of value assignment to boards--"What's the edge for W or B if the game state looks like this?" is basically a solution to that problem, since it gives you the counterfactual information you need (how much would placing a stone here improve my edge?) to answer those questions.
I agree that it's a much simpler problem here than it is in a more complicated world, but I don't think it's trivial.
DeepMind's go AI, called AlphaGo, has beaten the European champion with a score of 5-0. A match against top ranked human, Lee Se-dol, is scheduled for March.