I'm not sure I am reading the article correctly, but it looks to me that this new display tech uses less energy than EInk for the initial image creation, but then requires quite a bit more (0.25mJ/cm2 is greater than 0mJ/cm2, though still a minuscule amount) for continued display.

I would guess that they probably are able to get a crisper image or perhaps full color with this new display tech while still being optimized for low-energy pull.

Edit: Someone else posted this link which shows the Rdot displays do in fact have color capability - https://rdotdisplays.com/technology.