>we have a problem with giant cities where you cannot even see the sky anymore...
Our problem is, that we externalize cost to much. Moral people take care of their waste/byproducts and side effects -- unless they can't see it. Like invisible CO2, overseas exploitation or paramounting debt. We have build our society and lifeforms on top of these externalities and some day will be pay day, so it is reasonable to either limit consumption or pay for sustainable disposal now. Compact cities reduce metabolic cost of our processes and you can't really bring the luxury argument while looking at the current over all decline.