Salon has an interesting article on how AC has transformed American society. It identifies AC as being instrumental in allowing the development of the Sunbelt region, contributing to the decline in traditional regional architecture, and even in reducing the importance of public spaces in daily life.
I’ve lived without AC in a number of different places, including New York, which is mentioned a lot in the article. Honestly, living without AC is not so bad in most places. While air conditioning has had a major effect on how people live, if it suddenly disappeared, most people would quickly adjust.