Bestiality can be consentual... Ever had a dog riding your leg? :D
Rape... In general it's non-consentual but when a rapist gets caught, he will tend to make it appear consentual. (Yeah, she invited me inside for a cup of coffee, so I got in, ripped her clothes of and had sex with her even though she kept saying 'No'.) "No" means "Yes", right?
Rape and necrophilia can be enacted, though! And you could wonder if a movie where someone has sex with what apparantly seems to be a corpse is committing a crime if this corpse turns out to be a living person who just acted dead. (Or when the corpse was just some rubber doll with plenty of special effects.)
You can also wonder if a cartoon that contains a rape scene or other "illegal images" should be banned or not. Those Japanese 'Manga' movies, for example, display plenty of sex and violence and yet I don't think those cartoons can be banned. Unless you call it indecent images but then you might have to get rid of lots of paintings in museums and wherever else too.
I think that porn has existed for quite a long time anyways. It's just that the invention of the photocamera and the printing press made pornography a lot more common than it used to be. And so far there has never been shown a clear relation between porn and rape/sexual abuse.
There is a reason that we are hearing more often about rape cases, though. People are reporting rape a lot faster these days. Half a century ago, a woman would be too ashamed after being raped and would just kept her mouth shut because it would be a shame for her family. Today we know the woman is not to be blamed if she gets raped. If she said no, the guy should respect that. End of discussion about that. If the guys doesn't listen to that, I think his balls should end up in a small jar, separated from the rest of this rapist.
Still, in many countries women are still ashamed about being raped. Even worse, in some countries women are punished severely if they get raped. Makes them a double victim. (And the rapist often escapes without much harm to him or his balls.) I hate that!
I had a friend who was sexually abused by her father for quite a while. She committed suicide at age 16, though. Her whole life was messed up by what her father did to her. Yet no one ever suspected that her dad was this abusive. He was a very devout man who had a clear opinion against porn. He was also against sex before marriage and disliked homosexuality too. When he got arrested, they searched his house but didn't find any porn. (And he had no computer so no computer porn either.) Yet, while he disliked porn, he just couldn't keep his hands off his 11 year old daughter. As I understood it, she was sexually abused for at least several months before our school noticed something wrong with her. A teacher decided to talk with her and police got in action almost the same day. Afterwards, she was sent from one foster care family to another and I kind of lost all contact with her, until I heard she had committed suicide. I still don't know why she did that, nor do I know if her dad is still in prison...
But it tells me that a sex maniak doesn't need porn to rape. Besides, if I understood correctly, many rapist get their joy from their power. They have control over another person and that seems to be what turns them on. Rape isn't just about sex. It's also about control. It's forcing a woman to say yes when she says no...