Such has been the case with the strip "Funky Winkerbean" (which I usually read), as one of the show's characters dies of cancer. Some readers can't stand it: "I just can't stand [this] story line. … Comics are suppose to be interesting, funny and relieve some sadness. It is really awful that you would take up such a story in [the] comics section." (my response: then you're under no obligation to read the strip. Certainly no one's forcing you to do so.)
The strip's creator, Tim Batiuk, has an even better answer: "To readers who feel I owe them a funny strip, I would say I owe them the best work I can do. In order to do that, I have to challenge my expectations of myself and then I challenge my readers' expectations."