These two images are typical rural sprawl compared with Central Manhattan, on the exact same scale. Now I'm not an expert on these matters, but something tells me pollution, traffic and logistical problems would be much, much worse is everyone had their own plot of land.
Take a photo of the areas that feed those areas, though. Extremely dense, biologically depauperate urban areas combined with large contiguous monocultures is essentially the worst of both worlds. The best is diversity of urban form - smaller, highly dense areas surrounded by a mixture of managed and unmanaged natural and agricultural areas with diverse polycultural cropping systems. See work by Marina Albierti , e.g.