I like the idea of social housing, but living in a house built by the social sector of the economy doesn't always mean that social houses are poor and ugly. It depends in what kind of society you live. Is it a city (nation) strongly influenced by a laissez faire economy or a mild but for the city treasure much more expensive social democracy or maybe by extreme communism? One of the things I am missing in this kind of games are political idea's, having there influence how a city is ruled.
To bring these idea's into a city building game we need in the game two financial sectors, city owned property and private owned property, and a ground/property policy, including selling to and buying ground and property from the private sector.
In the beginning of the game, when nothing is built yet, all the ground is owned by the city. Roads (in the game) are always city property but zoning along the side of roads means in fact that the ground owner (thus being the city) made the decision to sell the relevant ground tiles to the private sector according the city development plan. Thus green zoned ground tiles to sims to built on their acquired ground their private owned houses, blue zone's to the private owned commercial sector and yellow zone's to the private industrial sector. The pro side for a city doing that is that it will receive property tax (based on the actual ground value and the set tax rate) from the private owners. This is almost conform the already existing system in the game. New in my idea is that the city receive a one time only selling income, based on the actual land value when it sells ground tiles to the private sector. The zoned ground tiles are definive sold to the private sector at the moment that the property building activity starts there. Before that you can reconsider your decision by dezoning still empy ground tiles without any costs. Zoned ground tiles were property is built on can not used any more by te city without (costly) consequenses due buying back the relevant ground tiles from the private owners for the actual!! ground and property value. The (realistic) fun having this suggestion in the game is that you as city mayor can't do what you want regarding the to the private sector sold parts of your city if the city don't have the money to buy the private owned ground tiles back. Rising land values of private owned ground tiles makes buying back private owned ground more expensive (very costly) and that can be a nice solution to fix the current existing unbalance in the game that it is i.m.o. too easy to make a lot of money for your city. Rising private owned ground values have a positive effect on the happiness of the relevant sims, but dropping values of private owned ground tiles have a negative effect on their happiness.
In my suggestion you can also built houses, commercial buildings and industries whitout zoning ground tiles. This is regarding housing the less or non educated (poor) sims in my suggestion social housing policy. In that case the city (you) build houses (and other real property) and maintain full control of what you are building on and remove from the city owned ground tiles. But now it is the city that must pay the price of building real property regarding what the actual costs are. And the city must pay a maintance fee and don't have tax income for its social houses. On the positive side, the city receive as real property owner each month rent money that is based on a set rent percentage being relative to the tax percentage private house owners must pay if they live on that location. Of course sims can't pay more rent for living in city owned houses than they can effort. Further there exist a income upper limit for the right to live in city owned social houses, this to prevent that richer sims can rent these houses. So regarding social housing the city can make the choice to save money by not building social houses or building cheap ugly and poor rent houses, or make the poor sims happy to let them live in nice good looking social houses for (much) lower rent income than real property market rent prices. But that has (some) negative consequenses for the happiness of richer sims, living in commercial rent houses or private house owners (being somewhat envious) not really liking that the city tax income they have paid is used to subsidize the housing comfort for the poorer sims.