The animation industry in America has been shifting at a fast pace as of late. We built up a lot of talent during the 30-50's with the greats putting their footprint into the sand. People apprenticed under them and learned from the seniors how to make great fluid and comical moments in animation. They then became senior staff on both Disney and some allowed themselves to spread out into other fields like TV animation. During the 80's and less so in the '90s the animation seniors were in force in TV animation. The Directors then where slowly pulled out of 2D animation forces of Disney and moved to Pixar as the production values and respect for the field was reinforced there along with better paychecks. So eventually the 2D animators at Disney just moved.
All the people that worked on the great things we grew up loving left for movie level production teaching the new kids doing work in 3D how to correctly produce timing and flow. While they added on their experiences of modeling and renders.
So where did that leave our TV animation companies? With nothing more than noobs behind the wheel it spurred a push to use technology ever more to fill in worker gaps and to remove overseas production. Welcome vector animation..., It's taken nearly a decade for people in the vector animation field to catch on to just "some" of the magic the seniors built in cel animation over the years. So maybe, in another 20 years we'll have really great TV animation coming out from here again. Until then, I'll be stuck watching Dreamworks and hoping.
Oh, and Japan, except for some notable 3D movies directed by the bigger companies..., most of the production was spawned out of noob animator startups. So they were always behind in 3D production since 2D labor was highly accessible. They're doing good now though, not great but good.
I will supply no references for my theory of this labor timeline as it is a horribly cobbled semblance of research and links. Though as always I am very happy to be proved wrong.