They probably are trying to find better ways to display images in color and NOT kill batteries in 24-36 hours as a new battery. That is a issue with the color isn't it? Limited power and constant battery changing?
I know my Bratz Muchiz liked wasting batteries. I believe the 2nd Pokemon Pikachu, Gold and Silver Edition, ate batteries too. I do not own the 2nd pikachu or a color tama.
I know the V-migo pets in greyscale sucked batteries like no tommorrow. And that was greyscale, that by itself. Not many parents bought that for kids. So they are probably sticking with the cheaper one layer screen here.