Personally I get neither the appeal of NTR nor the abhorrence, so I think I can look at this with a cool head.
I have no statistics, but it appears to me that NTR is probably more often represented in AVNs -- in fact very often -- than one would expect based on the number of people who specifically enjoy it as a kink. There are good reasons for it. To most people who do not have this kink it is far less offensive than other kinks they don't share, such as gore, scat, urination, or even just male homosexuality. This is in part because we are not dealing with the same kind of deeply ingrained taboo here, and because even if you dislike NTR you can get around that if you can temporarily identify with the cheater rather than with the cheated MC. Moreover, some forms of NTR are simply the porn version of what has been creating conflict and suspense in literature for thousands of years. It's hard to come up with a good AVN plot, and it gets even harder if you rule out cheating and jealousy as plot devices.
On the other hand, there are clearly some people with very strong negative feelings about NTR. And just like NTR appears overrepresented, the voices of NTR haters also appear overrepresented. I have never seen anyone post in the forum for an AVN: "There is no scat in the tags. Is there definitely really no scat here? And is there a guarantee that it will stay that way?" But for some reason, posts like this have regarding NTR have become very common. Also when there is NTR in the tags or in the description or even title, it's relatively common to see NTR haters in the discussion, complaining loudly about the fact. It's far rarer for people to complain about urination, scat or gore, even though that would make a little more sense. I think I have only ever seen such complaints in reviews, where they are more legitimate.