They did it to prove you can be successful in the business without swearing on their records. They never once said it was a personal reflection on themselves. Proof is in the live shows where Chester, among the rest of the band, swears like sailors. Also, they swore in the Pankake Festival DVD. They really never put themself on a pedistal by saying they didn't do it, period. They also didn't come off as pretentious asses about it either writing disclaimers about lyrical content.