Same goes for Bob's Burgers. I can't even tell that it's animated with Flash most of the time due to so few motion tweens. KaBlam! managed to look more fluid as well, and that was from 1996!
Bob's Burgers got an animation bump in the second season. The animation looks even better. There were some little lagging bits here and there the first few episodes, but now it looks like it's completely hand drawn. But then again, Bob's Burgers is the type of show that would work if it were stiff, (like Aqua Teen Hunger Force) but it wants to look as well animated as anything else in the line up.
And yes, you
can do hand drawn in flash. Most people stick to libraries of expressions (killing off the need for extreme, unique expressions) and motion tweens. But you can draw things frame by frame into the computer and animate it like a cel drawn animation.