That's not Hayden in the suit in those promotional pictures. Hayden wasn't available during that promotional shoot. That was just some guy they stuck in the suit. Don't you feel stupid now.
That is Hayden in the suit, and he looks pretty damn imposing, just like Bob Anderson did in the suit for ESB and ROTJ, even though he was a good 4 inches shorter and 50 pounds lighter than Prowse.