>i think the craft of the actor should manifest itself in
>service of a story, rather than the supposed story serving as
>a flimsy excuse for hysterical gyrations and show-offery on
>the part of the actor.

I mean, basically all of GOBs character is based on slapstick (because he's stupid), yet I don't think it stretches beyond what the writers need out of the character; he's not taking a pratfall in every scene.
Buster has to have this "young man making old man expressions" face because of the back-story of a sheltered youngest child as the only companion to a control-freak mother that weaned him on 30s era musicals.
Tobias, prior to the third episode, was a fringe character that was sort of a victim of his own flailing in attempts to keep up with his wife; when he became the self-aware actor of the show, and the punching bag for the writers and producers, he game this over the top characterization of a shitty actor which is really very accurate.

Everyone else is just sort of straight characters meant to react to the three physical elements of the show, except for George Sr who for all intents is playing in a one man show. Will Arnett is stock hammy actor, but traditionally that's not what you think of David Cross as so he's not just "being David Cross", which would be grinning-in-your-face-as-I-insult-you. He gets to piss all over pretentious actors, and I'm glad for it.