While I haven't played the Sims, since the second iteration. I can try to help you understand through what I remember, and I'm sorry in advance if my knowledge on the game in question is a little outdated.
The main reason which I initially was drawn into the series was the sheer amount of control that you got over the life of the people that you created. There was no preset goal, though I guess you could say the goal is to see how long your game can last, instead your given a bunch of tools, and are told to make these people live an eventful life. Now beyond that, most of what happens is within your grasp. You want to make their life absolute torture to live, sure you can do that almost as easily as making it successful. This is also partially what makes Minecraft so popular.
Also you never really get overly punished for destruction of your character, unless it's done by lighting the house on fire, the game will retain the property although now it maybe slightly to expensive for your new family to move into. This makes the game very easy to pick up and play. In addition, unlike some games The Sims is very closely related to real life in that the entire concept dressing people up, decorating houses, and living an eventful life is something that people should understand.
I'm going to cut myself off there otherwise I'm going to start devolve to rambling like an old crank, lol. Hope it helps, and I think have to try out The Sims again after reading this topic.