I think it would be a good idea to give an option to an animator where you draw something on a frame without keyframe, it will not copy the previous keyframe but creates an empty keyframe. I juggle a lot with Krita and opentoonz and I got used to opentoonz's method of inserting keyframes when drawing on empty frames. I personally want this since I rarely copy the previous frame.

This has been often requested, but there's noone working on animation right now.