Pros and cons.
e-Ink tablets are quite readable in daylight conditions and have excellent battery life but can't (YET) do color and are slow to "turn" pages.
LCD tablets are more flexible since they can do things like comic books and magazines, and they're more useable in indoor and especially low-light conditions thanks to their backlights, and they have higher refresh rates making them more suitable for multimedia content.
The article seems to state, based on tablet, Fire, Nook Tablet, and especially iPad sales, customers are more inclined to take the LCD tablet's flexibility of function over the e-ink's high readability. And of course, nothing has been mentioned on continued development of "converging" technologies that intend to merge e-ink's daylight readability with LCD's quick refresh and color capabilities. The wheel keeps turning...