Maybe because that's what Pratchett is so brilliant at: exposing actual social problems in fiction in a way that is less (?) threatening and in some ways more real.
Clacks are probably a big metaphor for something, like in Jingo. I read the whole book and thought Jingo was the stupidest name, then hit antijingoism in my history textbook. I had to read Jingo all over again!
Anyway, brilliant job in doing the clacks... I never really understood them, especially in Monstrous Regiment (quote from Henry Knox about women's suffrage, I believe, by the way)