I've been playing the sims since 2004, so this will be biased.
I play the sims not to escape my real life, but to explore and build alternate lives that can last only months at a time. The power to do so is very well realized in the sims. Whatever takes your fancy can be done. People often talk about mods being stripped from high profile games, buy if anything, the sims franchise disproves that. The mod scene is simply flourishing 11 years later, with near countless stuff you can add into the game, for free. The same goes for expansion packs as well. They have lots of great fully featured packs that add a hell of a lot to the game, yeah sims 3 does have a few rip off packs but you can always avoid that crap, I did.
But I think the best thing about the sims is that you can mould the world, people and buildings to you liking, like a cut down, people focused version of simcity. For the past year and a half I've been (very) slowly creating my dream town in the sims 3, complete with a dichotomy of people. Trying to individualise people to their very mannerisms is hard work, but can be extremely rewarding. I personally think having a creative mind adds a whole lot to the sims playstyle since you can create wildly different goals for each and every person you control. Just recently I have masterminded a family feud that had a wildfire effect and has fanned across my once docile neighbourhood. I'll ensure it ends amicably, but it was great fun playing out your own soap opera storyline.
Another save I'm a business man trying to commercialize the town without sacrificing people jobs but realize the change of management is inevitable. Some of the consequences are hilarious because often the same people you fire know you or your family.
There are endless opportunities in the sims games and if you are a person who loves to write your own story (per se) then the games allow you to write a few that will stay with you.