It's crazy how much SimCity cities look like the cities we've built for the last 75 years. Our cities really can be simplified to a game "fun" for someone to dive in right away. My thesis is that cities are oversimplified and stratified into easily separable blocks because they're easier to "industrialize" that way. This is causing crazy transportation requirements and isolation. If we mixed uses up a bit we could save on transportation overhead and be exposed to more things. The driver of this SimCity pattern of development is undoubtedly the single occupancy automobile. Sprawl works best for the car and the car works best for sprawl. Denser, mixed up uses work best with walking, biking, and transit. Conspiracy theorist in me says the auto industry influenced city planning from the ground up because they could profit off of it. Who profits when you walk more? Well, everyone... healthier bodies, healthier minds, more efficient transportation, etc. etc. etc.
My biggest problem with both SimCity and City:Skylines (its spiritual successor) is that neither allows mixed-use zoning, forcing you to rely heavily on either cars or dense (expensive) transit networks. It's like they can't break the mold of the US suburban mindset.
In the latter, while you can't build a building zoned for multiple uses, you can certainly very much blend zoning very thoroughly, alternating commercial and residential buildings as you go down the street. Of course, the simulation likely isn't sophisticated enough to make full use of that (people will travel across the entire map to go shopping). I can also understand from a gameplay perspective why this is the case.
It's very much because of gameplay issues. Theoretically the computer can simulate whatever model you can dream up, but the much harder problem is the user understanding, visualizing and editing that model with an easy interface that feels fun like playing a game, not tedious like doing your taxes in Excel or rigging skeletons in 3D Studio Max.
Think of the number of extra user interface panels and gizmos and views and pop-ups and menus that users would have to wrangle in order to build, edit, query, visualize, and maintain 3D multiple story mixed use buildings in a city simulation, instead of having a simple 1:1 correspondence between space on the 2D map and zone type.
The closest thing SimCity comes to mixed use zoning is multi-layered Arcologies, and the interface to those is pretty complicated and unwieldy. Imagine if every building and skyscraper in the city were that complex!
Sim Tower supports mixed use zoning (with different discrete rooms in the same building), but just within one high rise tower, not a whole city. It's as much a game about pedestrian traffic, elevators, queuing and congestion, as an economic simulation.
The Sims is whole a game unto itself at a different level of abstraction, that lets you build multi-story residential and commercial buildings with walls, doors, windows, furniture, etc. But it doesn't simulate "urban dynamics" between zones, just "personal dynamics" between the people and the architecture and contents of the buildings. The Sims 3 was scaled up so you could seamlessly walk around small towns, but The Sims 4 went back to focusing on houses or apartments in individual lots or flats, instead of expanding to simulating entire cities.
I've long had a dream of taking the source code for the original SimCity and changing it more to my liking. The newer version was nice for streets with curves, but inferior in almost every other way compared to the original. But I doubt I'll ever find the time to actually take a crack at it, so it will likely remain just a dream.
The original source is now available under the name Micropolis https://en.m.wikipedia.org/wiki/SimCity_(1989_video_game)#Mi...