This will ensure a longer battery life in case you sometimes read a book on the E-Ink display and only occasionally you browse the web or watch a movie.
An E-Ink display looks and feels just like real paper. It doesn’t fatigue your eye and you read from it just like from a piece of paper. One of the main advantages of using E-Ink displays over using a LCD screen is their lower power consumption. Amazon explains on their site: “Ink screens do not require power to maintain a page of text, allowing you to read for up to a month or two on a single charge versus hours on a tablet or smart phone.”
It’s easy to understand why Amazon would have thought of building such a tablet. The device would basically tie all the loose ends between its two most popular devices: the Kindle and Kindle Fire. We generally use our mobile devices for viewing animated media content, reading mails, reading books, playing games and browsing the web. Amazon can use both displays and choose to display media content on the LCD display while allowing us to view emails or read books on the other.