There's a difference between using electronics and merely keeping it on. I don't see why we can't keep the phone antennas on during flight. I'm with everyone who said the whole interference with airplane instruments is BS. But I do agree we probably shouldn't be actively holding/tinkering/using our phones during takeoff and landings.
They need to change their message. Instead of saying "turn off your cellphones", maybe they should say "put away your phones".