Actors are steeped in a world of agents and where the next job is coming from and what are their expenses and what is the hotel like. You want to take them out of that world and dump them into another world, so that when you meet them on the screen they don't seem like the guy who was in two others movies that year.
9/11 was a deliberate, carefully planned evil act of the long-waged war on the West by Koran-inspired soldiers of Allah around the world. They hated us before George W. Bush was in office. They hated us before Israel existed. And the avengers of the religion of perpetual outrage will keep hating us.