I'm pretty sure e-ink has a much higher ceiling for reflectance than TLCDs/RLCDs, so you'll be able to use it comfortably without a frontlight in a lot more situations which could more than make up for increased power usage. I think they are also naturally better in terms of glare compared to any type of LCD.

It isn't clear to me that eink's underlying display technology isn't good at the interactive computing use case so much as the implementations aren't optimized for it. There could be a position where more power than an eink reader is used but still far less than traditional active displays since unchanged pixels aren't driven.