I like to be able to sing along to songs when I'm alone in the car, so even if I don't understand the meaning of the words, I like to know the words.
I also enjoy word play, and Du Hast has some of that. So knowing the bit of trivia about 'Hast' and 'Hasst' being homophones in German and meaning 'have' and 'hate' respectively, and the main portion of the lyrics being wedding vows adds a layer of enjoyment to the song for me.