You can't really toss out a "here's a topic, discuss" without giving an discussion starter. And you did that, it's just that your starter was about your presentation and not your thoughts on hentai as art. Seriously, posting that would have been a good way to get this thread on track.
Anyway, a lot of the argument in this thread seems to be based around conflating fine art and applied art (or crafts). Fine art is art which emphasizes aesthetic experience and meaning, placing form before function. Applied art (and crafts) are the opposite, function comes first and foremost and aesthetic/meaning are secondary.
The line between them is blurry. A painting or print can be used in advertising, which is certainly applied art, whereas a sculpture made from welding rusted car parts together would likely fall into the realm of fine art. Clearly the medium doesn't define what is "fine art" and what isn't. Film and photography certainly straddle that line.
The reason I bring this up is because we can now focus our attention on pornography which can be filmed, written, drawn, rendered, etc. What line would pornography need to cross in order to be considered fine art? I argue that it can't. If it's pornography, it's created specifically for the purpose of getting people off. There was a >$1 million porn parody of Pirates of the Caribbean made a couple of years ago (come to think of it, close to a decade); it had a plot, actors actually acting as well as fucking, a musical score, costumes, etc. None of those things elevate it from being "a really expensive porn film".
The real question you should be asking is "What is Pornography?"