Some interesting discussion here about Bill Watterson and Jim Davis and it makes me wonder about this word, "integrity," that's being used. In my mind, integrity is to be honest and to do what you promise to do (unless we are talking about physical structures, which we aren't here, are we?). When an artist "sells out" is that really showing a lack of integrity? I guess it depends on what promises they made to... them…
If Watterson deviated and sold the merchandise he would have lacked integrity, sure. But someone like Davis is acting according to their ideals and intentions and so on; there is a lot of integrity present in the matter.
People use it to mean “they did something I disagree with” which doesn’t inherently overlap with integrity concerns.
I suppose you could argue that art isn’t meant to be commercialized in such a way, and so Davis lacked integrity to the discipline and trade. Some comic artists might say his approach takes away from comic artistry and lacks integrity in that manner. I’m not sure if that’s true or reasonable to say at all. Someone can make a comic for any reason they want as far as I’m concerned.
I don’t know what Davis is like personally, but from the outside and looking only at Garfield, it doesn’t appear that he lacked integrity.