Here in Canada we can only benefit for a few weeks from air conditioning, and in addition to the cost, and the unnecessary use of energy that other people have mentioned, AC has a couple of other disadvantages:

We live closed-up in our houses for half the year or more. So in summer I enjoy the outdoor smells of earth and vegetation that are mostly blocked in air-conditioned buildings.

In a crowded city, air-conditioning units actually increase the outdoor urban temperature. They just move hot air out of buildings and into yards and streets.

We seem to have forgotten how to use good old-fashioned fans, and old, passive cooling techniques that other writers have mentioned.