Comment by cubefox

The problem with this technology is that it uses conventional colored subpixels to create arbitrary colors via additive RGB mixing. This results in a rather dark image, because the screen swallows two thirds of the incoming light.

For example, if you want to show a red surface, you have to make the green and blue subpixels black, resulting in an overall dark red. This problem does not exist for colored paper, monochromatic E Ink screens. Nor does is exist for active LCD or OLED screens, which also use subpixel color mixing, but do not have to rely on ambient light.

The electrophoresis-based screens from E Ink actually support more than two colors (e.g. black/white/red or black/white/yellow for signage) without using subpixels, but that's not enough to create thousands of colors for arbitrary content.

I think electrophoretic e-paper screens are just not suited for subpixel-free colors, but other promising e-paper screen technologies have been abandoned a while ago.