I really dislike horror movies, often feeling rather sick when I watch them; they're sort of like a miniature form of torture. (While I don't have mirror-touch synesthesia, I do probably have stronger mirror neuron firing than most other movie viewers?) But I think I generally feel more revulsion against pain afterwards than before. Just the few horror movies I have seen are probably somewhat responsible for my general disposition of wanting to prevent suffering.
It's interesting that a stereotypical horror movie watcher is perhaps the opposite of this: The usual image of such a person is a young person, probably male, and probably somewhat macho. It's also likely that watching horror movies repeatedly leads to desensitization. So a strategy of aiming to make people care more about suffering by promoting extensive consumption of horror movies would probably backfire.
Watching disgusting films is a unique experience that has made me a slightly different person from who I otherwise would be. This isn't surprising, perhaps, because apart from being a victim of violence or torture oneself, there are no other ways to encounter cruelty so graphically and forcefully. I wonder: What other human experiences are similarly powerful, to the extent that I should seek them out in order to broaden my perspective on the world?