This is all highly reductive. Not sure what you're basing your assumption about porn on. If you're not turned on by something in real life why would you seek porn based on it?

There are plenty of people who long for a life of riding around on a horse swinging a sword at things or exploring the outer reaches of space on a futuristic craft. On the contrary; I'd say that the fiction that people select is highly correlated with their escapist desires.

Keep in mind, im not saying that people who enjoy Fifty Shades want to be raped. But there are enough people with rape/domination fantasies that it makes sense to unearth its sales as a proxy for repressed desires. And these desires are antithetical to a culture that calls for more fairness/equality between the sexes, or at least the claim that deeply seated biological urges don't influence a person's thoughts and behaviors directly.