Just for some historical perspective:

Beggar's Opera was probably a bigger cultural shocker in 1728 than Threepenny was in the 1930s. It was certainly, from a popular standpoint, considerably more successful. It was a parody of the then-becoming-very-popular Italian operas, which featured formal music and the doings of the nobility; Gay used pop (folk) tunes, and concentrated on the underside of English life.
    He was no less cynical than Brecht. Read the lyrics. Such as
"But gold from law can take out the sting
And if rich men, like me, were to swing
T'would thin the land such numbers to string
Upon Tyburn tree" (to tune of Greensleeves)