Another factor is that the ubiquitous sight of male pain desensitizes us to it. Violence against males is literally all around us. Relevant, too, is the context of the violence. The main purpose of the portrayal is to get the audience angry enough that it will watch the rest of the story to see to it that the villain is punished for his transgression. Even more poignant, men are the victims of virtually all violence in comedy.
Male pain is the only pain which actually brings laughter and applause.
Although it is politically correct to dismiss the importance of violence against men, the preponderance of male victims in the media is mirrored by a preponderance of male victims in real life. Men are three times more likely to be victims of homicide. We are so desensitized to violence against the male body that, only for men, does real violence overlap with entertainment. Given the protest against simple portrayals of violence against women, imagine the howls of anger if real women were really beaten into real bloody unconsciousness, and it was broadcast on network television as entertainment. Think about that the next time you watch a boxing match.