This is a great thread you've started. I have a few opinions about the matter. Hopefully, even if you don't agree, they make some sense.
I've done quite a bit of writing in the last few years, mostly for NaNoWriMo. I've managed to steer clear of profanity. It's really very easy to do. You can leave it out without having the characters sound cartoony. I really don't like reading books where the characters are swearing constantly. I especially don't like it when I see them taking the Lord's Name in vain, because just reading it feels like I'm actually doing it in my own mind.
As for sex, I've left that out of the work I've done, also. When you have a story that takes place over a short period of time, it's really very easy to do. It's unfortunate that the media constantly bombards us with characters that sleep together on the first date... quite often. I did write a story where one of the characters was a married man who was attempting to cheat on his wife early on in the book, but nothing happened as he was foiled in his attempts (even then, I tried to keep the dialogue clean without being sexually suggestive). Additionally, the character was killed halfway through the book.
Which brings me to violence. Yes, in the writing I've done, there have been plenty of fights and action scenes, including the use of weapons. There were also a few grizzly deaths in the book I wrote for NaNoWriMo last year, which was a sci-fi horror story. It wasn't anything worse than you'd see in a PG-13 movie, but to me, it got the point across that the characters were in a life-or-death struggle (it was sort of a B-Movie type thing where they were fighting snakes. Not the most original concept in the world, but fun nonetheless).
So I see it like this. Swearing is completely unnecessary, and fornication shouldn't be glorified. I believe those are the things that cause life to imitate art. Sure, there are unbalanced people out there who have been influenced by movies/TV shows/video games to commit acts of violence, but I see that as a rare aberration and also an excuse. In my opinion, swearing and illicit sex in the media have a far worse impact on the everyday lives of consumers. I do believe that people who watch TV shows where the characters are sleeping around end up with a very casual attitude about sexual activity that plays out in their life. And the swearing... if you watch enough R-Rated movies, it becomes a part of your daily speech. I could be wrong, but I just think violence only rubs off in very rare and disturbed cases.