A note on 2. Any potential attack on Stormwind, or any other major city, will ultimately fail without dealing lasting damage. There is actually no reason why the Alliance can't get a fishpump moment in on a defensive victory, provided the attacking force is sufficiently smashed. The overall point is that Garrosh needs to feel like he's still a serious threat even as we storm the gates of Orgrimmar. Showing that his reach still extends beyond the city would be a way to do just that.