Yes, and he very likely was aware of the issue back in 1995. In an article about him, someone mentioned: "It used to be that 'you did it forever, no matter what

Yes, and he very likely was aware of the issue back in 1995. In an article about him, someone mentioned: "It used to be that 'you did it forever, no matter what the quality was,' says Moore, who doubles as a Times news editor. 'The new camp [of cartoonists] says that when the quality of the strip starts diminishing, you get out of the business.'" (http://articles.latimes.com/1995-11-16/news/ls-3760_1_bill-watterson http://articles.latimes.com/1995-11-16/news/ls-3760_1_bill-w...) His "resignation letter" was naturally too short to contain his complex thoughts on the subject.