LOL, Matt and Trey bashing is hilarious.
The way I see it. Doing the episodes right before they are set to air, that made the show fresher and topical. Since they can finish episodes in just days they can actually comment on things that were actually going on. Saddam Hussein popped up with his beard just days after his capture. There was imagery mimicking the Elian Gonzales home siege right after it happened. Family Guy is NEVER that quick or up to date or that biting and witty with their political satire and commentary.
Isaac Hayes situation was what exactly what should've happened in that episode. Trey Parker and Matt Stone were reflecting how upset they were about it, that Hayes had to leave because the Scientologists got (huffy) about it. The episode was not only hilarious and relevant but it was also heartbreaking. Also the death of Chef, its South Park, that's EXACTLY how it should've happened. There's a different between Mary Kay Bergman committing suicide, which I don't know any details on, then Isaac Hayes being forced off the show he's been a regular cast member of for the better part of a decade because of a "fruity, little club."
Unlike the Simpsons in a similar amount of time, South Park has managed to remain funny, fresh, and relevant.
South Park as seasons went on really got better as a show. Family Guy already feels like its waning. I've never really seen Family Guy really able to accomplish a character arc like South Park has for Mr. Garrison over the course of their show. Or really a character evolve the way Randy Marsh has. Randy Marsh's evolution has been one of the more recent gems of the series.