Re: I would prefer convenience at the cost of a few deaths
"Of all the changes since 9/11, the only one that will actually prevent 9/11 style attacks is reinforcement of cockpit doors."
You forgot one other change. Before 2001-09-11, hijakers took over planes primarily to hold people for ransom. Most passengers would be released with little harm. In this condition, not resisting gave the best chance of survival. The hijackers of that day changed the condition. I suspect most passengers today facing the same situation would actively fight back. I also suspect the hijackers would be dead before they could get into the cockpit, even without the reinforced door.