On the subject of making the doors more secure, why don't they just use two doors in an "airlock" type setup, i.e. : Only one door is ever open at any given time.
The only airline in world that really takes security seriously is El Al, guess what sort of door set up they have?.
Already the numbers of people who want to become airline pilots is reducing and the inability to allow youngsters to visit the flightdeck will have a long term effect on the numbers of kids who will want to do a job where you are locked away in a cubicle for hours on end.
No one has been allowed to visit flightdecks in the US for years, they are not exactly short of applicants for airline jobs over there.