Rather sad to read through this thread - dam, courtesy seems to be well and truely dying.
When I fly it's usually longhaul. So switching off my reader for the half hour either side really doesn't matter all that much. And yes, I think it's not necessary having been on flights were nearly every passenger happily was talking on the mobile phones and we didn't crash (obviously
).
Nevertheless, why put the staff through the stress? They are doing their job. It's courteous to follow their instructions. (Yep, I was raised under the old school system
).
And as the thread shows, no one really knows if it does harm or not - I am not talking about the ONE reader you might use, but the 300-400 devices every passenger has in the pockets / bags.
As someone mentioned previously: it's the airlines plane, they can impose any darn rule they want. You don't like it, stay at home or take another airline.
Be nice and switch off - lot less stress for the flight attendants and the passengers around you.