Even highly graphic animation styles still require you to understand shapes and how they turn in space. Otherwise you're going to end up with an extremely limited action palette for your characters. Flatness should feel intentional, not the result of lack of skill.
Anatomical/technical drawing skill is obviously vital for a 2d animator but a huge percent of the job is being able to visualize objects in 3d space. 3d animators have the xyz grid so the camera can move independently but 2d animators have only their brain and a flat page, their skill IS the camera.
Fable Siegel, Lackadaisy Showrunner
Kasey Gifford
I've been thinking a lot about visible vs invisible skill layers. i.e every craft has outer layers of skills that laypeople can recognise, and inner layers that you need expertise and experience to perceive at all. Could y'all think of examples of visible vs invisible skills in your own discipline?