Why rappers use bad words in their lyrics,though they know its harmful for the society?

I know rap is the most popular genre,and the best way to describe an event or a story.But if rappers stop using such words like a**,di*k,f**k........,then it will be the best for everybody.Parents don't want their child to utter such words like the rappers do.Even i like rap song,and i think if such words are avoided,then their is no problem.children are the backbone of future and they must get the best in their life....god bless them....