From what I can gather people aren't dissapointed that Spore's not SimEverything. They're dissapointed because it's a bunch of mediocre clones of better games, akwardly glued together?
Почему у вас есть так много хорошие игры в россии

I guess Space Rangers makes up for Tlon (and if that was a grammatically correct sentence, my mind will be blown).
"In DF, if I go talk to a guy in the town, he'll tell me how he was a hunter for a few years, and then a fisher, and now he farms for a living. And two years ago this giant ate his mother. And so on. And he's not a major person, he's some random peasant."
I think this is the biggest difference between a lot of go anywhere, do anything RPGs and Dwarf Fortress. DF uses all of this procedurally generated, random, whatever stuff to make the world more detailed and interesting -- essentially, there's not pre-set story, but one actually IS created because the game keeps track of all of this historical crap. Whereas, in something like Daggerfall, you're just offered a bunch of random quests and they rarely matter.
I mean, look. If you want to roleplay that you're seeking vengeance because a troll killed a bunch of people from a town, you're not going to have to be pretending all of this elaborate backstory stuff actually happened. They troll really DID kill your past five characters.
I mean I guess you can say that in summer, what Dwarf Fortress does -- and since it keeps coming up, Space Rangers 2 -- is that not only does the game let you do whatever you want, it also REACTS to you doing this in a far more significant way than "Way to go, champ! Your rank just went up with Guild X!"
In regards to games spoiling one, though, Ultima 7 did that a lot. After playing U7 and going back to, say, Oblivion, my immediate response is "What do you MEAN I can't interact with every single object, no matter how unimportant it is?"
By the way, SimEarth had SNES and TurboGrafix ports, both of which had improved graphics over the PC version and some pretty good music.