I found an article/interview with Al Jean from February 2002 (in a paper from Fort Wayne -- I forget the name of the paper, sorry; I cut-and-pasted this from a computer search database) which I find very interesting in view of some of the discussions that have gone on in this newsgroup. Here's the relevant excerpt:
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"Lisa's Substitute" became a rallying cry of sorts for outraged fans a few years back.
During the 1999-2000 season, the show took a turn toward the broadly comic. The writers offered up a spate of farcical, slapstickfilled episodes that were satisfying on a certain level, but offered little in the way of emotional impact.
Internet pundits squawked, lamenting that episodes like "Lisa's Substitute" were apparently a distant memory. Writers responded by having an overweight, comic-bookcollecting character pop up periodically with the words "Worst Episode Ever!"
In hindsight, Jean says, he believes those fans had a point.
"I'd rather have (fans like that) than not have them. It's like that old saying, 'The opposite of love is indifference.'
"It's important to keep the show from getting too unreal. I'm guilty of that. I tend to go for the cartoony. I've been part of the dumbing down of Homer."
One of the problems, Jean says, is the nature of writing sessions.
"When we read a script with the actors, we tend to base its success on how many laughs it gets. It's harder to take into account the finer feelings that may be evoked. 'No laughs' tends to be interpreted as, 'The thing's not working.' "
Ironically, the relatively laughfree "Lisa's Substitute" was not one of the writers' faves.
The backlash made Jean realize that - as important as the show's reputation for astute cultural criticism is - the heart of "The Simpsons" is the family bond.
It may take more abuse in "The Simpsons" than it did in "The Waltons." But it, nevertheless, endures.
"There's no guidebook for new writers, but the basic idea is that people should be able to relate to this family."
Jean says there are limits to how stupid, opportunistic and lazy the writers can make Homer.
"If he starts to seem cruel and abusive, then people stop identifying with him."