The vastly disproportionate number of films with violence as it's main theme begs for a rational. I think one of the reasons is that people that were interested in the physiology of violence, and the effects and techniques of violence had an advantage in our evolution. They might have been better prepared to thwart violent attacks, or to attack more successfully. Throughout history, resources undoubtedly were much harder to come by then now. Competition for food and resources was often actualized by way of violence. Peaceful people were often killed for their resources, so that even farming communities often had defense plans. The way we extol civilizations that killed others as a way of survival (the Huns for instance, though history is replete with examples) I think tells more about modern human psychology then we might like to admit.