The CAFE regulations are not causing this, in fact they are acting in the opposite direction, making vehicles safer. More aerodynamic vehicles are more fuel efficient and more likely to have lower and more sloped fronts and thus are also safer for pedestrians.

Furthermore, vehicles with higher fuel efficiency tend to have smaller engines and thus also have shorter noses and more sloped hoods which make them safer for pedestrians.

The only connection with the CAFE regulations you can make is that they are obviously not strict enough. Especially when it comes to trucks and SUVs. And I fully agree with this. Stricter CAFE regulations would help not only with emissions but with pedestrian safety.

The main reason for the difference between a 1990s f150 and 2020s f150 is that people have been preferring to buy bigger trucks and Ford has catered to that preference by making the trucks bigger CAFE regulations be dammed. To their credit Ford has done some very good r&d work, trying to keep their ever larger trucks relatively fuel efficient, such as by their very well publicized conversion to aluminum. But they could and should be doing more and the government should be doing more to force them to do more.