Yes, but the iPads are now used for flight reference the whole flight. If the flight crew can have one on a few feet away from the instruments during an actual IMC approach, what will a few passengers with them in the back do?
Because......
With the WiFi turned off.
Another important factor is that they have control over the device as they have with the WiFi connectivity for the passengers as well. They can shut it down if necessary from what I know.
You can argue that the FAA is being an overly cautious bureaucracy but the simple fact is they can't do testing on all the devices out there that passengers carry that may interfere with flight-relted equipment. Even if the frequencies used by consumer cellphones/tablets/computers are different than those used by aircraft-related equipment you can still get 'leakage' or unintended radiated emissions from those consumer devices that could interfere with frequencies outside their designed operating parameters, especially if the consumer gear is damaged. To put it in layman's terms, you drop your cellphone and it might not be just a shattered screen or scratches that is wrong with it.
I would prefer the FAA continue to err on the side of caution on this issue, better someone not be able to 'like' the new shoes they got for the flight or yap to their bff about the creepy guy next to them than have a single accident.