This might be a deeper analysis then anyone wants, but here is my opinion. I think the reason why American culture is ok with violence of any sort, but not ok with sexuality of any sort, is because sadly violence is very real. It is common place to see someone with a gun, it is not horrifying to know someone has a conceal carry permit. People get shot on the street over traffic disputes. Shot by cops who are using excessive force, people shoot into crowds for no good reason. Violence is real in America and so because it is real and we are familiar with it, it shows up on our big screen. Sometime the violence is to make a point about how violent our society is, sometimes it is to glorify our Heros, but it's something we see everyday. Even back in the 'Wild West' violence was an everyday occurrence, and a means to provide justices, or seek revenge.
Sadly what America lacks is love. Love understanding and intimacy. Therefore when those things show up on screen they either make people uncomfortable, or they are some twisted into overly sexualized scene that have no real emotion behind it, and do nothing for the plot or development of the characters. I look around everyday watching my friends fail at being in relationships, over and over again. Cheating is everywhere, and those who have more 'traditional' approaches to relationships are shamed. Sleeping around is glorified. If you fall in love with your high school sweet heart and have only ever had sex with them, than you are seen as having missed out. You should 'live a little' before settling down. But that makes you selfish, and guess what one trait is are to overcome in a healthy relationship? Selfishness.
We have woodstocks and more people having open or polyamorous relationships. If that is right for them, then go right ahead, the issue is that that is also being pushed onto our society through media, and usually in a negative way. The drama of a pair of people in an open relationship but one of them falls in love with someone else. The drama of a happy Lesbian couple but all of a sudden one of the 'lesbians' fall for a man, or the drama of the 'successful business lady' cheating on her stay at home husband. All with the excuse that we are 'sexual' beings and seek out pleasure. However if a murderer pleasure is to kill, that doesn't making it right. So all these plot line of cheating and going around 'seeking' your selfish pleasures are horribly negative. The sex becomes about pleasure and temporary passion rather than love and commitment.
That's why I hate it, and don't want to see it, and am really getting sick of it becoming more lewd. Maybe I'm just a hopeless romantic, but I really hate how almost every ABC or NBC show has a bunch of people cheating or jumping into bed with someone else.
Plus the sexualization is hypocriticall in that, it's find to see a lady jumping up and down on a man and moaning, but everyone burst a blood vessel if two men kiss on screen. Not to mention that if two girls kiss on screen it's usually for the pleasure of men. Example Veronica and Betty from that live action adaptation of Archie. They kissed to get a shock value, that was most likely just fan-service for the male audiences.
Rant over, lol.