Earlier quoted context omitted.
There are huge numbers of opportunities to trade off inconvenience against reduced death. For example, we could prohibit radios in cars because the music and adjustment can be distracting and lead to collisions. Or ban cars entirely since they're much more dangerous than walking and public transport. We could require everyone to wear an N95 all winter. Ban phones for the entirety of the flight, and prohibit books as…
The inconvenience vs risk threshold here is similar to bucking a seatbelt which is hard to argue is a poor investment. Aircraft may be very safe on a per mile basis, but those risks are extremely concentrated around takeoff and landing. Which are fast events, so the risk per second is relatively high even though flying is generally much safer than driving.
It really, really is not. Seatbelts actively prevent injuries from sudden violent phenomena. "Paying attention" does absolutely nothing to reduce the forces you are subject to in the event of, say, a collision with a Dash 8 that was on your runway at landing. It helps post-incident at best.
And I have "paying attention" in quotes because I feel like people are ignoring how attention actually works when they propose things like this. Human brains actively reroute focus in response to stimuli - like, say, a collision with a Dash 8 that was on your runway at landing. That's the whole concept of "a distraction". Hell, just a car braking particularly hard is stimulus enough to capture its passengers' attention, to talk of a plane landing going wrong in such a catastrophic manner. By the time the cabin crew is even ready to begin an evacuation, whether or not a person was fiddling with their phone (or just staring into space) some seconds before the incident seems highly irrelevant.