The F-bomb. That big of a deal?

I wonder why people get upset whenever they hear the word "fuck" on TV. It's just a word, and is it really something to get upset about? I know some people, parents especially, get upset whenever they and their kids hear the word "fuck" on TV, but whats the big deal, because it is not as if a kid is not going hear it from someone else like a friend, or someone walking down the street, or the parents themselves.