Obligatory disclaimer: of course I don't in any way condone the slaughter at the Charlie Hebdo offices which was a horrible event, but like Glenn I found the universal praise - and pressure to praise - Charlie Hebdo, as opposed to just recognizing the evil of the attack. was disturbing. Their "satire" was never funny, it was just racist and provocative. "I will spit in your face just because I can" level humor. Often there is nothing that is recognizable as a joke, not even a Homer Simpson "it's funny because it's true" joke.
Defenders of Hebdo say they're "irreverent" to everyone equally, not just Muslims (as is now obvious!), including the genuinely powerful. But the punching up/punching down distinction matters, especially when the punching down isn't even funny. I mean, sure, I get that even racist jokes can be funny (which does not defend them, just that you can mine anything for actual humor, whether or not you should), but again printing pictures of Mohammed is only funny if you think deliberately pissing people off is funny. And that's fine, I'm not calling for them to be shut down and certainly not to be slaughtered, but Eric Cartman has more sophisticated racist jokes than the Charlie Hebdo cartoons in question.