Why does Canon insist on making a new battery adapter for every slight body variation? They size every body revision just a little larger or smaller, which necessarily requires a new adapter. What a waste.
I think they could standardize to 3 body sizes and maintain them year to year with very little effort. It would simplify their supply network and show some long term planing.
(yes, i know the obviously trite answer is "they do this to make money")