You both seem to arguing with extremes ends of human settlement configuration - planned empty mega suburbs like this one in Burma and hunter-gatherer bands before the dawn of agriculture. Sort of a contrived comparison, isn't it?

Re: affordability - I don't know about Burma or Brazil, but in the US, safe, medium-high density neighborhoods with walkable commercial districts and an active civic life are very expensive compared to the car-bound exurban cities in the same metropolitan area. So much that they are only accessible to the upper-middle class to wealthy.

Also, cities didn't invent slavery or bring on disease. These were on the increase from the onset of agriculture due to the demand for labor and the co-habitation of humans and domestic animals.

In fact, there may be genetic evidence of this: There was an article linked on HN yesterday that tried to explain the apparent loss of marker diversity in the Y chromosome after the advent of agriculture to male agricultural slaves being denied the right to reproduce.