I think violence and sex in games are fine. America as a culture will fight anything they can/ Violence and sex in games are mostly looked at as bad by parent to protect their kids. While I believe there should be a limit on how much violence and sex are in games kids play, it should be the parents job to watch what their kids play. Violence and sex in the games themselves should't change.
Also if you look at Japan they have a lot more sex and violence in their games. Also much less crimes in their country. I'm not saying that they are related, it could be the difference in culture. However, there are studies out there that show that violence in game lessen a person's desire to commit crimes. The studies show that the players relieve their desire to commit crimes through playing the games.