I agree with this suggestion. I think it's a great way of solving the "fog problem" using (mostly) things that are already available on the site. My one question would be how this would affect manual troop deployments. Currently the deploy phase is "Round 1" (which I don't really like). In a perfect world, I'd like to see manual deployment and "Activation" happen in Round 0. But even if that is not addressed, I would favor this just to take care of 95% of the fog problems (i.e. every game except manual deployment).
As to the comments above: I don't think this is overblown. Even if there are just a couple games out of 100 in which this makes a difference, it still may make a difference to high ranked players that depend on a certain number of wins to keep their ranks. In most games, the dice and drop will matter more than the ability to see a couple extra territs. But there are quite a few games, especially on big maps, where an opponent can block you from seeing a critical territory in that first turn.