The biggest reason for the replacement wasn’t actually to bring the airlines into the 21st century technology, but to save fuel. According to American Airlines: “American’s pilots will be using the iPad, which is the only FAA-approved tablet as a replacement for paper-based reference manuals that weigh 35lbs. This will save AA an estimated $1.2M of fuel across all of its planes annually, based on current fuel prices.”
They are also looking into providing the flight attendants and other personnel that use manuals as part of their job with iPads.
With the pilots and crews using the electronic tablet, it may also open the door for passengers to continue to use their electronic devices during take-off and landing at some point in the near future.