Comment by Qwertious

Not the person you responded to, but basically ereaders are more appliance-like than phones. Being able to put color-requiring documents and textbooks - which tend to require a lot of flipping back and forth, and thus need high 'refresh' rates (BTW e-ink screens don't 'refresh', they just update) - into an ereader let's you go offline more completely.

Obviously ereaders are appliance-like in part because e-ink screens have bad color and update rates, but at least they'd be practical outside in direct sunlight, and it's not like ereaders would suddenly become technically impossible to be appliance-like.