Earlier quoted context omitted.
More screen estate in the same space would mean a denser panel - higher hardware cost. Also would mean lower battery life - higher user cost.
I implied a bigger panel. Same width, but 16:10 instead of 16:9. This toolbar thing isn't free either wether it's literal money we're talking about or power consumption.
Well, if it's e-ink, there's no power consumption except when it changes. Plus it's probably a lot cheaper to find a small strip of e-ink panel (given the number of Kindles etc.) than to find a Retina-class 16:10 panel.