Surely it's their unreserved approach towards bringing out fantasies and not being afraid to get a little violent...ok make that very violent, I know the extreme ones exist just haven't been able to stomach them. While we're in the business of comparing the two, I'm sure everyone is aware that there is a creative side to Western porn as well, it's just a rather small community. The mainstream ones that sell well often focuses on just the sex and any theme/plot is rendered irrelevant once the action gets going, unlike in JAV where the student would beg for the teacher to stop before ejaculating in her. Their roles actually mean something.
I am a fan of the superheroine genre and some privately made clips are pretty well shot. The key is that the director understands the need to focus on giving the heroine a strong presence and the bondage/dominance over her which makes it all the more satisfying and gives it a great erotic buildup. In fact a good amount of them are like ZEN titles with no actual sex involved. However the one thing that is definitely absent in western porn is the shyness/embarrassment aspect. The women are always total sluts and have no problems getting naked from the first second on. There is so much they can learn from JAV on that...not only is seeing a beautiful woman reluctantly undressing herself hugely erotic, but the various reactions (defiance, anger, or even emotionless) is a huge turn on.
I think the most creative medium however remains hentai. There is a great scene in Seito Kaichou Hikaru where the girls (established as strong, heroic demon hunters in the beginning) are coerced into standing on stage in an auditorium and stripping themselves. The crowd make lewd comments about their bodies while the 3 girls give you a diversity of reactions: reluctance, fear, and rage. The leader then gets her virginity take in front of everyone in a cowgirl position, the most vulnerable, humiliating and exposed position possible, especially for the fact that she would have to be the instigator for the copulation. The whole process takes almost an entire minute as she first has to announce that her virginity is about to be taken, describe what's about to take place with the penis and vagina in an obscene matter-of-fact manner, then deliberates as the dick is too big and wonder how it could ever fit. She struggles to even just fit the tip in for a while before the guy decides to ram up on her in one fine, powerful thrust. There's so much emotion here and the buildup keeps kicking up a notch slowly, it's brilliant. I think I can conclude that great porn for me is not the exposure of the body, but the exposure of the mind (trying to be pretentiously philosophical here lol).