To me, this is an issue of relativity. While it is absolutely true that wieght is an important factor in survivability, it is only true in a relative sense. It isn’t the absolute wieght of the vehicle that makes it safe (or dangerous), its the relative wieght of the vehicle compared to the one its going to hit.
The problem is that there are huge cars on the road, and a growing number of tiny ones. Its the disparity that creates the danger. If we all drove tiny cars, we would all be safer. The problem only exists when one person decides that its his right to drive a tank at the expense of everyone else’s safety.
To me, this safety issue, coupled with the geopolitical consequencies of relying on unfriendly people for our engery and with the ecological consequences of the lager vehicles, its a no-brainer to outlaw SUVs and mandate vehicle size.