I remember one especially biting criticism from a comedian or filmmaker who basically argued that we have it backwards with the ratings for violent films, and instead should rate certain war movies so that younger people actually CAN see them, and rate other, "fantasy" violence higher so only adults who can discern the difference can see them.

I think the example was "Saving Private Ryan" which is rated R, but in this new scheme would be PG-13, because it depicts war realistically. The James Bond movies, which are PG-13 because they have no gore, should be rated R, because the violence in them is depicted unrealistically: with no consequences, with effortless skill on the part of the killer, and with clear cut "good and evil" roles. I'm sure I'm butchering this argument, but I found it to be an extremely compelling one, if a bit too optimistic that this would ever change.

In games, see the recent article on Jonathan Blow that was posted to HN, called "The Most Dangerous Gamer". There's definitely a related discussion among certain game makers about violence in games.

Mere reproduction-level sex can ensure the survival of a community just fine. Plus, sex can quickly get communities into trouble (rivalries, mainly, also people becoming absent-minded etc).