Something else to keep in mind is the history of The Sims shows that greatness doesn't always start out as anything like the game which you know. The Sims started as a house building simulator and the sims were just intended to "live there" and provide feedback without direct user control. It was basically SimCity except taken to a micro level where you built a "house" to make sims happy/comfortable, basically like other "sims" variations such as Tower and all that. The Sims grew out of an experimental concept which was nothing like the end product. What makes things fun is realizing when something like a simulator needs a change of focus. SimCity and related items are obviously about the city and had a lot of interaction with the player to keep things interesting. SimHouse was falling on it's face until it was realized that to keep the interest level, interaction with the sims was required. Once that realization was made, SimHouse became no more and The Sims were born.
Interestingly, the groundwork was there long before that change was made, in the sense that Will Wright had years earlier played the game Little Computer People, which was a 1985 game where users played with a premade house that had 1 virtual person in it who was quite a bit like a sim. Will Wright said in an interview that he consulted with the designer of Little Computer People while developing Sims 1. The Creatures series was also involved - it was originally pitched as "little computer ewoks" by its designer, and, while I couldn't find a direct statement that Will Wright had played it, it would be really surprising if he hadn't, since it's so relevant to his interests and was big in the 4 years before Sims1 came out.