I really don't understand how this is an advantage for iPad readers though.
By and large, you should read with some light, if only to avoid eye strain that can cause headaches and fatigue. I realize this isn't true for everyone (or at least not in youth), but generally speaking wouldn't it be odd to be sitting in the dark and reading? 😕
Now of course the one glaring exception to this is when a significant other wants to read while another wants to sleep. However, if one can afford an iPad, shouldn't one logically be able to afford a separate chair to sit in for reading? Is it really a terrible inconvenience to read in a different part of the room (or in a different room) so that the light doesn't distract your partner?
Perhaps even more importantly, why is reading in bed an imperative? Generally speaking it isn't recommended because it can contribute to acute insomnia.
And no, I don't mean to preach about any one method or the other because I realize that people will do what's comfortable for them, but I just wanted to raise some logical objections with this oft mentioned "advantage."