Researching arc animation online on Pinterest and YouTube I found some animations in Disney that use arcs to make the animations look much more appealing to their target audiences. For instance the first video is for the shot in Big Hero 6 where Baymax and hero are flying across the city when they fly over the bridge. It is quite an obvious arc shape as they fly over the top of the bridge in a very simple arc shape. But because they move in this shape it helps to make the scene more appealing as they are not even flying they are sort of sliding across the air in this arc shape which helps to show a smooth movement across the screen.
The next video is for Sher Kahn in the jungle book where he is talking to one of the vultures or Mowgli I think and he sort of shakes his head after snaring at the other character and walks off into the jungle. The shaking of the head and the movement in the legs indicated to me that the animators used arcs to get those natural curves/ arcs in the animation to help make the movement look more natural and to have a nice smooth animation as appose to a jumping from frame to frame. The use of arcs particular here helps to show the dramatic expression of the character as when he shakes his head you can clearly see a form of arc shape that helps the animator to show of that expression, whilst getting a nice movement.
Both of these animations with arcs help to make the animation look more appealing to the target audience, as the arcs although you may not even notice them, help to build those natural movement in characters to help make the animation flow nicely throughout the scene. The arcs also help the animator with timing as when you go up in the arc the movement is quite slow. Then as it goes down the arc the action gets faster helping show some of the dramatic and natural movements in these characters.