Lots of innovative ideas here... though I think you're missing something.
I would add a dimension of politics to the list, which to me would bring the feel of SC3k and SCS to its logical next step.
In SCS, as you stated, your sims have an impact in the way the city runs. In SC3K, your sims would actually complain about things in a variety of ways (unlike SC4 where all we got was a approval rating), that is, want your casino torn down, taxes lower, etc...
So where did the latter go? Not in SCS apparently.
In the initial city set-up mode, we would be able to choose our government style:
Mayor-Council (typical multiparty representative democracy)
Direct Democracy (non-representative, good for small New Hampshire-style towns [forgive me, I'm another "blind to other cultures" American])
Oligarchic Council (the rich elite run the city)
One-Party Council (Good for Authoritative Societies)
And so on... you can fill in for me.
The purpose of these are variations on the ways sims can give you feedback on your mayoral style beyond their happiness level. In mayor-council mode, for example, Sims are likely to form political parties to give you conflicting ways on how to run the city. The caprice of the people and your previous decisions will impact what sort of buildings you can build or allow zones to build in the future. This is where the council will come in: This eight-member group will, by a percentage, will either prohibit you from building certain buildings even if your city qualifies for it. They may also make certain buildings less or more expensive. For example, a "Green Party" majority will prohibit the mayor from allowing "Metal Casting" type buildings to develop in Away Zones, but if they only consist of 33% of the council, the cost of allowing "Metal Casing" developments will increase by 33%.
By contrast, one-party states eliminate this system.
The mayor's "policies" are dependent on the buildings they build. By comparing the percentages of each developments a mayor has allowed with the percentages of persons with certain ambitions and thus different visions of what buildings the city should have will impact what sort of members are on the council.
This system for the Mayor-Council type will have the effect of encouraging the player to build certain decorations not necessarily to balance societal values or make the area look nice, but they will also have an impact on what sorts of sims will occupy your city. In other words, you can have the people agree with you if you invite those people that would already agree with you! For example, The hedge will attract "art" and "executive" type sims and cause more "industrial" type sims to leave town to small degrees.
My ideas aren't complete, I don't have all the time in the world to sort and iron them out. That's what a forum is for, isn't it?
And before I hear those who don't want to have all this political realism in the town, I understand, but I hope that it will be generic and rational enough not to cause controversies.
For the record, this would probably be better suited for a SCS update rather than the penultimate simulator.
(Yes, I'm aware of how old this thread is. Deep Thought's ideas are just so timely not to comment on them.)