I understand Simmel wrote at the turn of the 20th Century but I question whether the amount of personal freedom attributed to inhabitants of the city applies in modern society. Are we all not confined by the expectations of those with whom we interact regardless of environ? Regardless of where we live we still have close social networks that influence our actions, beliefs, and atttiudes. Therefore, the city simply consists of the combination of multiple "closed" communities in one location but the pressure to conform to reference group norms is no less. Yes, I understand that in the city you may have more contact with unknown others but I would argue in modern society this also occurs in small towns, contradicting Simmel's claim as I understand it. The more relevant question may not be locale but rather how strong are the social networks the individual belongs to and the amount of influence they exert on the individual.
OK, I've rambled enough for tonight.