This post has been brewing in my head for a while now, since I started playing the Sims game on Facebook. Prior to that I'd played a few so called "social games", but came quickly to the conclusion that there's nothing social about them. What Zynga refer to as "social gaming" is "repeatedly spamming your friends with begging requests for stuff". Whilst there is some form of social-ness in that you're all part of the spam-fest, I don't really feel that it's a good kind of social.
With the Sims, I'd expected something a bit different and for the most part, we do have that. Sure there are the quests where you have to collect X items, but you can just find the items by doing stuff yourself. Although I think there are some people who are still in the Zynga mindset and just send out requests straight away rather than spending the time to just collect things themselves.
But there still doesn't feel like there's any socialness about it. Your Sim never really encounters any other Sims. The Sims you meet are sort of alternate reality copies that only exist in your Sim's worldview. Like I could visit izzy_stradlin's Sim at the same time she's playing. But she won't see my Sim and I won't see whatever it is she's doing to her Sim.
There also isn't anywhere to visit aside from your friends' houses. So unless you add your friends, you'll be stuck with the one NPC Sim to visit. You can't pop in to some central location and meet new Sims there. Which is why on the forums and places where players can post messages related to the game, there are dozens of requests for people looking to find more people to add. If the game was actually social, these would be a feature of the game. You'd be able to meet new Sims and add them outside of them being your Facebook friend.
I wish I had an idea for a game that was actually social, cos I so could write it and let people lose at it.