rinkytink had the right idea, it was because there is no nudity shown on broadcast / public television in the USA, one would have to subscribe to cable TV in order to see any. Also, even very young children watch the Super Bowl, and parents like to have a say about when their children will first be exposed to such visuals as nudity, so that they can give a lesson about morals at the same time. It upset people mostly because there was no warning that the incident was coming, for those who may have wished not to see it. It wasn't an accident, like accidentally falling out of a dress, it was secretly planned. And, there isn't actual sex on American broadcast / public TV, only the actions leading up to it, and then the rest is edited / cut out. You can only see unedited R-rated movies on cable TV.