I think there's something analogous to the anthropic principle happening here. This match is happening now because Google realized we are in the moment when Go AIs are passing the top players in skill. Two years ago, Lee Sedol would have won easily. Two years from now, AlphaGo will win easily. In either case, the match wouldn't have happened at all, or wouldn't receive the same amount of attention.
That assumes a continuous function of Go AI ability. It's not continuous, as alphaGo proves. AlphaGo was a huge leap in ability from the best previous AIs. It was a totally new method, and one given Google scale resources at that.
AlphaGo isn't a fixed strength, though. It's substantially stronger now than it was in October. Obviously it's not a completely continuous function, but I think it's close enough to cause this effect.
Right, but alphago was the closest thing we have to the transition - yesterday ais were too weak, today they need to try them against world champs to validate their work
