But I like hentai because it's fantasy. Doujins bring the whole "childhood crush of characters" from various anime full circle by seeing them get fucked.
I've also developed some fetishes over the years thanks to it.
Personally I find the stories silly but interesting and isn't as cringy as when real porn goes into story... -_- ugh. Also I like the artistic freedom and the ways they draw expressions and stuff and some of the silly nonsense positions.
That's not to say I don't like real people. But when I watch that stuff I end up venturing into more interesting areas.
Like many of us, I discovered hentai because I like anime and manga: though as to how I discovered hentai, I really can't remember (probably internet). I do watch regular porn (and enjoy it) but in terms of preference, I choose the hentai life/way.
The reason is because it fulfills many of my sexual fantasies, the art-especially how some panels and shots are framed- really turn me on. The story is another major component, hentai manga is better written, told, executed, and pleasing; especially facial expressions that are almost impossible in real life. Pacing is another plus, I can read either slow or fast, take my time on an illustration, easily skip to the best parts, and very relatable on a personal level with characters and situations.
With regular porn is just not the same. Sometimes I feel the pacing is slow and have to fast forward to the juicy parts. The acting and dialogue is sub-par, couple dynamics is stale, talking occasionally irks me, and finally, though I have respect (and an attraction to some porn-stars) the actors are the least important factor when watching porn.
Basically, with porn I am just watching people having sex and satisfies my lust. But in terms of both physical and mental lust, it is hentai FTW because the story, setting/framing, and characters satisfy my lustful cravings.
As to why others don't like hentai; I guess it's because they are not used to it, or were told it was wrong and only weirdos are attracted to 2D characters. I think it's a shame because this thinking doesn't allow them to explore their sexuality to the fullest. (I've seen so many sexual examples in hentai that I want to try).
Personally I've always found the scenarios/setups and stories to be hotter than the actual sex and with hentai every fantasy can come true unlike normal porn where budget matters a lot more and even then it looks garbage. That said, often vanilla hentai is just plain sex -which is pretty boring- so it isn't all flowers either. :)
People who are repulsed by hentai think it's mostly tentacles porn and controversial material. I like hentai because it's usually prettier or more interesting than fake moaning porn vids