All these links prove is that you can use Google. You are missing my point that the bar in question is vastly behind the initial point of impact and not significantly low enough to help any of the factors written about in the links you provided. Especially when you consider the bar is covered with a plastic guard that would funnel a pedestrian UNDER the Jeep.
I am, by far, NOT an expert. So I am not explaining exactly how Jeep designed the bumper and why. I am only giving some possibilities as to why they designed the bumper this way or that. It is an interesting field and one I follow as a course of my employment. However, I have not hired an expert in this field because by the time we are looking at the damages to the pedestrian, it is already too late and usually liability is clear, that being completely on the driver.
I am not here to prove anything. Only to assist. Remember, we are talking about a STOCK jeep. Looking at stock Jeeps, the pedestrian would not get funneled underneath. They would be impacted right where the knee bends, then giving them a chance at a reduction of a femur fracture. Most vehicles have bumpers heights right where our knees are. And I agree, that deals more with bumper height. But making that bumper softer, with less reinforcement behind it, would give the pedestrian less acceleration of their head into the hood. If it was a slightly softer blow, then their head would not get up to speed as much, thus reducing the amount of force the head would have to endure when the pedestrians body lays over the head. I believe that the links went into this detail quite well.
Does that make sense? Maybe I am not explaining it correctly?