I was with you up until the "it concentrates the population" paragraph. You're dead wrong about this. Areas of high population density that allow very low population density elsewhere are better for the planet _and_ result in lower service costs. If you provide miles and miles of paved surfaces to get to those distributed people, you cause increased erosion and decrease infiltration into aquifers. It's also much cheaper to provide infrastructure and services on a per-person basis if those people are close together. If you compare for example an apartment building where 100 people live close to a police station to a McMansion at the end of a mile-long private road 20 miles from the police station, you can intuitively understand much more maintenance will need to be done on the transmission lines and roads that go to the McMansion vs. the apartment building--and that's before even dividing that increased cost by like 3 for the McMansion vs. 100 for the apartment building.

Additionally, when houses are way spread out, no one walks anywhere, which virtually guarantees when the McMansions go shopping, they're parking in an enormous Walmart parking lot that is itself causing more runoff and erosion and contributing to the urban heat effect with its concrete and asphalt surfaces.