Yeah - I did say that it's a bit like Lisa's tiger rock
Still, I don't think literally rolling back the changes to the doors made post-9/11 is a good idea. The two-people-in-cockpit rule and maybe some refinements of the way the timed lockouts work is probably a better way to reduce these kind of incidents than making the doors less secure. If you make the doors able to be completely locked, as in this incident, then it makes this kind of incident possible. But if the door locks CAN always be overridden by someone outside (with a code/other means of authorization), then the reverse situation becomes possible - a crazy/suicidal pilot who has been removed from the cockpit can get back IN. There was a recent incident in the US where this same situation occurred in reverse
There is no complete solution since there's always a human trust factor involved. There are upside and downsides to being able to lock, and not being able to lock, the door.