For what it's worth, the game is rated 12 in Europe (well, where I am). Having an actual 12yo in the house, she's been playing (well, started with TS3) since she was 11 and I wouldn't really have been comfortable with her playing much younger.
There are definitely things that could be added to the game that wouldn't in the slightest affect the current rating and I don't think the game *needs* to go up to a rating that's any higher to be enjoyable. The thing is, ratings are generally less based on things like violence or death and a lot more by how explicit sexual themes are (and that whole debate is a long one and not particularly pleasant). So no, I don't think the rating needs to go up, there's plenty of space for the inclusion of more interactions and activities and things for Sims to do without the rating changing.
The game being toned down for everything has nothing to do with whatever people call PC culture either (honestly, that's just a buzzword that gets misused a lot). More with those who scream "think of the children" when it comes to content that's even remotely suggestive.
