Lack of end goals
I agree that the Sims franchise has pretty much gobbled up the simulation spectrum of game play for best picks. If you don't like playing Sims because you don't have end goals, make some. Legacy challenges, prosperity challenges and royal kingdom challenges add to the fun and give you a goal if you feel you need one. Because of the open ended game play you can design your own goals. Want every type of ghost, great, want every type of skin, hair and eye color in your family tree, wonderful. Want your town overrun with aliens, or vampires, or werewolves, get to it. I think the open-endedness of the Sims games is one of the things that makes it one of the best games out there.
Oh, and I'm going to have to give tropica a look now.