Despite being low-tech, a second person in the cockpit to simply open the door is worth more than a thousand cameras to record video for the media afterward
Murexway
The reason for this crash was twofold! Firstly a mentally ill pilot determined to put his name in history by murdering 150 people who were in his care.
Secondly the door system which was designed to keep terrorists out was used to keep a terror (ist ) in to do his evil deeds
The answer is not in Cabin crew but a means of the locked out pilot gaining access to the flight deck and overriding the pilot inside.
In this case it was a mentally disturbed pilot inside but also consider that while one pilot is out of the flight deck a terrorist could in a flash push in and with some knowledge stop the other crew member entering.
There has to be longterm a system of overriding a terrorist or mentally sick pilot from blocking access