If the U.S can live with a strong European Union and European common market, there is no reason why a similar Latin American and Caribbean body should be a problem.
The upshot is that, whatever the reason why human body hair has shrunk, one reason it has not disappeared completely is because it warns and protects those who sport it from the attentions of hostile insects.
Auto-immune diseases are caused when the immune system, for some reason, decides that a certain type of the body's own cells are foreign and starts attacking them.