Well paxboy it appear your casual dismissal has been rather rudely disproved. Three armed hijackers caught yesterday attempting a 9/11 scenario. Glad your in the back,maybe you can talk them out of doing anything.
Welding doors shut and crating alternative entrances is hugely costly and probably unworkable for the present fleets.
It's here, it's now, and they will try it again. Sooner we grasp that and decide how to best deal with it the more likely it is that we will be able to keep the industry going.