A way to reskin existing sprite animations

Unity has been doing a good job creating new tools for 2D and I love that, but there's still something missing that should have been added a long time ago. A way to reuse existing animations with different spritesheets.

If I create every animation clip (idle, walking, running, attacking, etc.) by hand carefully placing each sprite on specific frames for one character spritesheet once, why do I have to redo the whole process all over again for other spritesheets if I use the same spritesheet format which has all of the same animations with the same amount of frames and the same sprite layout?

Why do I have to either remake the same animation each time for every spritesheet I add or resort to using a hacky workaround like replacing the sprites during runtime and wasting processing power?

I don't know how to solve this problem. Could be neat if you could assign a source texture to the animator so it would know where to pick the sprites from, so you could even load a different spritesheet during runtime. Or have something like the new prefab variants for animation clips where I could choose the source image from where the sprites are picked from. Or even just make the animation clip files readable in the text editor so I could just quickly edit the sprite references instead of duplicating the clip and drag&dropping 200 new sprites into places.

As it stands now, current animation tools could be made much more 2D friendly and efficient for this kind of workflow.