I’m not too impressed with Sit Down, Shut Up, and neither are Fox’s viewers, who, like me, still enjoy King of the Hill more even though it’s past its peak. (Which is not to say that Fox is wrong to want to find a fresher animated series to put in the 8:30 slot, just that SD, SU may not be it.) It might get better; it might not; but so far it looks very suspiciously like another example of something I’ve noted before: truly successful prime-time animated sitcoms rarely originate at the writing end alone.
That is, the most successful prime-time cartoons all started with drawings that were developed at the same time as the series idea; instead of coming up with a concept and then seeking out artists to illustrate it, The Simpsons, King of the Hill and Family Guy all had a look to match the concept, with the same person responsible for creating and designing the main characters and setting a visual style that everyone would imitate. (Mike Judge drew the four guys from King of the Hill before he even knew exactly who they were.) This is not to say, as hard-core animation buffs often do, that only artists can create animated shows; these shows all have written scripts and non-drawing showrunners. But it is important that the characters should look the way they act, and that the overall look of the show should be inseparable from the way it’s written; that usually seems to come about when one person has a hand in both aspects. Those three shows have some pretty ugly drawing, but the drawing is inseparable from the writing.
The flop animated prime-time shows often look like somebody had the idea and then hired a crew to draw it for him; with Sit Down, Shut Up, we have a show that was supposed to be live-action (like its Australian predecessor) until Mitch Hurwitz realized he’d have an easier time selling it to Fox if it were a cartoon. (Something similar happened with The Critic, which was intended as a live-action vehicle for Jon Lovitz, and became an animated show when Lovitz wasn’t available to work full-time on it.) I’m not saying that this approach can’t work; it works in comic books, where an Alan Moore can write a comic and then give it to somebody else to draw. But it usually doesn’t work in prime-time TV, where — if the characters are not designed by someone who writes for them — they usually wind up with the sort of generic, bland look the characters have on SD, SU. And bland is way worse than ugly when you’re doing a prime-time cartoon.