Good point, and there’s another thing about Groening that irritates me: inevitably, he starts phoning it in. The final year or so of the Life in Hell comic strip could be summed up as “All Ackbar 'n Jeff, all the time,” and I never found the Ackbar 'n Jeff strips to be funny.
As much as I miss The Far Side and Calvin and Hobbes, at least Larson and Watterson decided to end them rather than let them slide into a rut.
