Cities are build over centuries, not months. For such a utopia to be in the least sustainable a rigid form of population control must be implemented, lest the burgeoning population continue on the doomed path of our society. Such cities cannot expect to be capable of sustaining our current levels of population, and conflicts in the decision of who composes the inhabitants of such utopic and progressive instalations may warrant attention. The first awnser would be that those who finantially contribute to the establishment of such polises, but in the end when the world is finally up in flames, so to speak, the unprepared, hopeless masses will engage in general revolt.
If I were to make a synopsis of your arguments, I would say that your arguments lack extensive abstract forethought. Not that you're a bad argumentalist, or that you lack thoughtfulness, only that the reason you fall short of agreeability is that of your failure to recognize enough perspectives.