Personally agree with you, @Shepard...I see no reason for cars to be added. I see a lot of lots and homes in the gallery where the creator used the size increase tool to make the decorative/toy cars as big as a real car and then put it in a garage or driveway, and I personally don't see that it adds anything. First thing I would do if I used such a lot is delete the car (and re-purpose any garage to be a skill-building area or some-such).
If I lived in a world where I could insta-travel anywhere like my Sims do...I certainly wouldn't own a car.
I also didn't really care about them in TS2...and in TS3, only cared because they let my sim get places faster. Which, ironically, is only because the open world concept made it take annoyingly long to get anywhere. Heck, load screens in TS4 are way faster than the open world travel....its the reason I no longer actually miss open world, even a little bit.
I'm with @AbraKadabra, I'd much rather have a new world or vacation world. Especially if the new world included more apartment-style housing.