I don't think homeliness and aggression are negatively correlated. Look at a cauliflower eared fighter. You have an association of that kind of truck with farmers, but it could just as easily be rednecks with rifles. Doesn't have anything to do with the design.
The front of the truck is sharper angled, the hood is actually forward so it appears like a shark; the grille takes up a larger percentage of the front of the truck.
The modern F150 is rounder, with a smaller percentage devoted to the grille, and has a flat front. If you size up the 1980 F150 to the same size, it would be much more aggressive looking - you can actually see this because the 1980 truck, when lifted, looks positively mean.