[Nasrudith]

Well for one people who paid for expensive real estate or had it appreciate in value won't be keen on any sort of devaluation whether from newer shinier buildings, an affordable housing project, or crime rates.

That is in addition to price per square foot rise from building larger scale - while more efficient in infastructure and land usage it may start requiring things like seriously deep foundations and pilings as opposed to a stack of bricks and mortar as a foundation. However while a high density area may wind up more expensive than prefabs at the outskirts not building isn't going to make things cheaper until demand collapses. Essentially it is complicated - part raw goods-and-labor economics and part selfishness tragedy of the enclosures essentially.