Nowadays it's really hard to find an enjoyable game that appeals to both parents and children.
When I was growing up I didn't have the sims, the sims had just came out when I was already playing first-person shooting games; I was corrupted at an early age because hello kitty didn't suit my video-gaming needs.
The sims is great for families to agree on, the violence is minimum and sexual themes aren't as bad (I mean, they named it 'Woohoo' for crying out loud!). If the little 'uns couldn't play the game due to extreme nature then what's the point of making the sims? My 9 year old cousin plays the sims, why would I want her watching and instructing murder. Although I would really like a 'mature' rated Sims; it just won't work out.
I can guarantee that Maxis EA makes a good portion of their budget from the age range of 8- 16. It would probably take a lot of time and money to make one specifically aimed for adults. I don't know about you but I play the sims to make and control a virtual me with a virtual happy family. I don't play the sims to kill all my neighbors.
So we're all different and the sims is one of those games not filled with violence, murder, drug abuse, and alcoholism. Quite frankly; I like it. Perhaps in the future they will consider a mature rated "Sims," I highly doubt they will be taking the Sims away from so many people though.