Suburbia allows you to ensure that your neighbors are able to afford to buy, rather than rent, a minimum quantity of land & construction (and usually therefore have a large amount of their net worth locked up in the value of that property), that they can afford transportation to and from wherever the nearest commercial center is, tends to limit population flows, and insulates the neighborhood from anyone who doesn't have their own independent transportation.

This selects for a higher quality of neighbor, which has positive externalities (eg, "Good Schools" and low crime rates) that balance the obvious costs. Alternate legal mechanisms for enforcing these constraints have been banned, so we use the zoning code and make a lot of theoretically neutral noise about Property Values.