I have to side with Don on the whole “Sims” thing; though it is largely a “sandbox” game that happens to have a goal system in place, it is basically an architectural/decorating simulation. In fact, I seem to recall Wil Wright saying that it started out as a landscape program that eventually morphed into the idea for The Sims.
I think if you look at it as a simple matter of “achieve these goals by doing these things with your character”, then yeah, The Sims (and its sequels) are pointless, because yeah, you might as well focus on real life (and some would argue that point regarding any game, but they're not here.)
But if you look at it from more of a “God Game” perspective, you are In Control of a whole flippin' neighborhood (or two), and you call the shots. Unless you're the head of one of those… whatever you call those organizations they sometimes make you join if you move into a neighborhood (I forget the name)… anyway, it's still a level of activity that doesn't mirror real life unless you're a cult leader. Or a persuasive chairman of a homeowner's association, that's the term!
And there is something fascinating about seeing the AI characters running around doing their thing, on a level never seen in the likes of Sea Monkeys or ant farms. I mean, when my lederhosen-clad Sim showed up to my wife's Sim's house, rang the doorbell, and then slapped her silly when she answered, I knew it was going to be a hit.
And talk about DLC — Where else could you have Mr. Bean and Dr. Evil living together in perfect harmony? (I'm referring to the first Sims game. I never got into The Sims 2 as much.)