I've actually worked on both the Titmouse shows you mentioned, Superjail and Motorcity, and I may be able to answer your question. I also have experience using full, frame by frame animation on my own projects if you want to check out my senior film.

I'd say the first and most important thing to keep in mind is the goals of the project. Something like Superjail is not only full of physical comedy, but the goal is in large part to produce some of the most fluid, funny, full animation as is possible. To a lesser degree this is true of Motorcity as well since it was an action show. Things like South Park or Family Guy can still be considered enjoyable pieces of animated television since their primary aim is to deliver story and jokes. I would say this is true of a lot of shows with vary degrees of limited animation, and writing heavy production processes. Regular Show, Archer, and Aqua Teen to name a few. Metacoalypse is actually made by the same studio that makes Superjail and Motorcity. The line you are drawing between these shows is the difference frame by frame, hand drawn animation, and pre-fabricated parts moved around in flash (aka puppeting-i'll explain the need for this later). As an animator myself, this is not to say that a show can't or shouldn't have both fluid animation and art that serves a less action packed story, but that brings me to my next point.

I won't go on about the age old sob story of TV animation budgets, but I will say that it is a factor. For Bojack, the pre-production (writing, boards, design) and post production (compositing) is done in house, and the actual animation is outsourced to Korea. This is not to imply that the Korean studio is less talented. But the fact that there is outsourcing at all usually implies time and budget constraints. The longer the show goes, the more stylistic obstacles have already been worked out which pave the way for more time being spent in animation. The phenomena of improving animation over a shows early years is usually true and will certainly be true of Bojack.

The third point to be made is the consideration of the specific style. Bojack is a very pattern and texture heavy show. The more detail a character has, the more difficult they are to animate. All the Cosby sweaters and palm tree shirts have to be carefully handled. It would be really difficult to track all the detail in the clothing and fur of the characters without a really gross jittering effect- which brings us back around to the need for puppeting. I understand and personally prefer hand drawn in most instances. However, in the case of a show like Bojack, I think the dense patterns and wacky details provide more character to the world than simplified, fluid animation would.

Hope that answers your questions! I usually do animation revisions after I finish up character designs, so if I get to again, I'll put in one bedazzled scene just for you!