y'know there is a reason people read books.
It's to get away from all that crap. I personally don't mind violence and gore (the more the merrier XD), as for sex...ehh I don't really care much. It doesn't add to the story most of the time in any significant way except for driving the love life of whatever character. It adds a lil depth, sure, but it isn't relevant to the plot most of the time...unless like, the book is about sex.
See the problem is real life, you think people would imagine and write about all these places better than the dreary world we live in, because they loved real life so much? I mean, people read books heavy with sex, probably because they simply...find pleasure in doing so. Same as with violence and gore, it's an outlet, a way to...live your fantasies through the words of another.
It comes down to taboo in the end. What's socially acceptable and whatnot. I personally don't care what you do in public, so long as it's interesting and isn't harming anything besides someone's dignity and pride heh.
When people say "real" characters, they mean someone they can empathise with, someone who goes through a deep sense of character development and isn't 2D so to speak. Most people see sex as needless and that it just gets in the way of story-telling, a "filler post" so to speak. And violence/gore is a turn-off for alot of people in the end as well, some people enjoy it and feel that good, descriptive gore adds to a story and really gets that dark and gritty feel, but majority of readers are the sort who read simply for the wonder and lightness that reading brings, an easy and enjoyable read, not something heavy and evocative. Also there are triggers, some people react adversely to such content, whether it be due to an event that happened to them, to someone else or something that they dread themselves.
Uh, there's my two cents.