There is literally no end to the inanity of bureaucracy.
And it's not like if something goes wrong I won't notice. They'll probably be a big thud or other loud noise to get my attention.
As the engines were throttling up for take off, I put my fingers in my ears to (I'm an acoustical consultant and my livelihood depends on my ears so I'm a stickler for protecting my hearing) - the FA sitting across from me saw me do that and told me to go ahead and put my headphones back in.
It's silly when the plane is almost parked at the gate, everybody stands up, and then the plane jolts to a stop against the blocks, causing a whole plane full of people to fall all over each other and get hurt because they couldn't sit down for another ten seconds, until the bell rang, like they were told to.
It's silly when the cabin door opens at 10,000 feet after takeoff, nearly sucking out passengers who, thank god, decided not to ignore the "keep your seatbelt fastened" warnings (the plane descended/slowed down and the attendants were able to get the door closed. The flight continued to Germany without stopping).
Hey, you know that live/die seat up/down joke? Turns out it's not about you; it's about not making it difficult for the people in the row behind you to evacuate.
Can you imagine the sighs and groans of the first-world aggrieved, if they were instructed to temporarily cease their addictions?
Um, so we're to believe it's the headphones that caused this? Most likely if the plane is skidding all over and there's a major emergency, the headphones aren't going to prevent someone from noticing. I'd be far more worried about sleepy passengers or something. In fact, in your scenarios, you wouldn't even be in an exit row, as you'd be apparently too disconnected from reality to verbally say OK to their request for assistance if needed prior to takeoff.
If the policy were about making sure that people were paying attention, then they would interrupt people sleeping, reading dead tree books, wearing earplugs, or doing anything else that takes their attention off of the attendant. They don't.
The policy has been retconned into being about attention, but the claim that it's about paying attention is belied by actual behavior.
This is all total nonsense, cell phones don't interfere with pilot communications and unless you put all the cellphones right next to the radios which are of course in a big shielded box up front!