People in cthe middle ages in ciities were wealthier and healthier, and free. People in the country were slaves or tools of the local lords. City air makes you free they would say, cities were filled with free people, and run by guilds generally, smiths chief amongst them. Other cities were more merchant ruled chiefly. The nobility forever looked down on commerce, everything except agriculture and war generally.

You couldn't just move into a city, you needed an in, like getting accepted as an apprentice in a guild.