[mitthrowaway2]

Thanks!

Weight matters for a vehicle -vehicle collision, but for a vehicle-pedestrian collision, it's nearly irrelevant. (This is because the physics goes like M/(M+m); there's an asymptote, and once M>5m it's practically the same as infinity).

But height (especially of the front hood) is very dangerous, both for collision interactions and visibility. That's more or less why the chassis matters from a pedestrian safety perspective. Vehicles getting taller makes streets more dangerous, even if they weren't getting heavier at the same time.