i found myself needing this today, you should add this 
the work around i made in this picture was to sweep across the edge from a side sketch, scale one end down, then subtract the new swept body from the main body.
this could be added as a subtool in the Chamfer/Fillet called “Variable” or something. you would select your edges, and on each end there would be a drag arrow/scale grabber to adjust the effect - thus giving you the same effect.