In modern times it became very fashionable to treat the city as a form of human coexistence in a definitely negative way due to a variety of reasons: both the industrial plants and streets overfilled with cars produce most pollution on the Earth, people have to live in overcrowded conditions, drink water full of chemical substances, eat food of uncertain origins and so on. However, can the city really be considered to be responsible for our troubles?
Yes, conditions of life in your average city are far from ideal; but is there any alternative? The Earth’s population is growing every year, and the only way to simply feed all these people is to create specialization: a larger amount is concentrated in cities producing material commodities, services and information, and a lesser amount lives outside cities, specializing in agricultural production. Even if all the people leave cities and start growing vegetables in order to feed themselves (in order to save the environment, presumably), there won’t be enough space on the whole planet where all these low-tech agricultural productions can be placed.
Besides, cities are nothing more than a natural development of human settlements. Since people always strive for effectiveness, they tend to gather together in order to cooperate effectively. The amount of parasites that attaches to such groups is the unavoidable price that has to be paid in order to achieve that level.
All in all, in my opinion, cities have much more positive traits than negative ones. And mostly because the ones who are so opposed to them cannot offer even equivalent alternatives, let alone better ones.