Even if we ignore the manufacturing and material costs, changing over the entire production infrastructure (from injection molding to electronics and final assembly) is insanely expensive and would effectively shut down production until all of the verification runs are done. This way they can continue production for the unaffected regions.

I'm not covering for Nintendo (they can burn in a fire for all I care), but I have worked in an electronics factory and knew some of the process engineers: any kind of change is a massive pain in the ass downstream.