Or maybe people who want e-ink are a single-digit percentage of the market.

If a consumer does research, as I did, and looks for comparison of the eInk of the Nook and of the Kindle, you quickly discover side by side photos of the Nook and Kindle and conclude that the Kindle eInk is better (it does use a more current version of eInk than the Nook after all). If you wanted color - you with w/ the Nook because that was the option you had out of the big two, otherwise, with the Kindle.