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.
IDK comrade, the carbon cost of transport of food is not really that big in comparison other factors. The idea of increasing the capital intensity of farming by an order of magnitude (without, mind you, a commensurate decrease in labour requirements) by farming vertically doesn't really sound like a realistic goal in our lifetime we have other things to deal with that are more important.