Since I don't actually think that electronic devices pose any threat to the operation of the aircraft, I think this one is a "mind your own business".
That said, it is annoying when people think they are "above the law" or "above the rules". It's like a silent DYKWIA, cause I'm better than you! However, there are sometimes consequences. I have a friend that is an AA FA based out of IAD, and she told me that she actually had security deplane a passenger from first class after that passenger refused to turn off an iPad, and was belligerent about it. I also witnessed a guy that was ignoring the "fasten seatbelt" sign, got up and was in the aisle when we came upon a big turbulence bump, and he was knocked off his feet and flat on his face. Karma's a ......
I've said this before and I'll say it again, when the rules are not enforced, only "rule followers" will follow the rules. Other people will not.