It would be helpful to be able to create a single set of animation settings and apply it to multiple elements. I have three use cases in mind:
Create a folder of elements and apply an animation to each element in that folder (the timing should/could still be different for each item). Similar to applying layer styles to folders in Photoshop.
Create an animation template that can be applied/"attached" to multiple elements such that each one is optionally (via a checkbox) updated automatically when the template is modified.
Be able to set some parameters and apply them to an arbitrary group of elements, such that the elements in that group can be added dynamically, either by user interaction (e.g., a custom action that generates sprite elements that get added to a looping sequence) or after rendering (e.g., a CMS that generates an unknown number—at time of export in Hype—of elements dynamically added to a sequence).
As for #2 specifically, we have some brainstormed designs for this feature. Symbols ended up taking away some of the need so it became lesser priority but I still think would be great to add.