Bringing full colour _and_ high refresh rate would move these out of the eBook world into more into every day technology. There's definitely a market for colour eInk monitors, tablets, phones, etc. but the technology just isn't there yet. More and more people are wanting to disconnect from tech or at least minimize its addictiveness and a colour eInk screen would be a great step for people. That way they can still watch youtube, take photos, scroll their apps but the experience will feel less saturated and alluring.