Most porn involves people who are enjoying the act, both male and female, so they aren't really experiencing humiliation. I think it's actually more likely the opposite of what you're thinking - the sheer shamelessness of it is probably more appealing to most people.
Well, the quality of the actoral work in the majority of these productions is clearly improvable. My general impression when I have seen some fragment of a movie of this genre - many of my (male) friends are charmed with them - hasn't been watching people enjoying it, but exercising an act in a repeated and mechanical way. I prefer the robot movies regarding mechanical acts, honestly. On the other hand, without pretending to pass for a radical feminist and without trying to ruin the enjoyment of the people, there is something of truth regarding the conversion of the woman in object.