Putting cctv in the cockpit has not been accepted by pilots or airlines. Privacy issues have been cited by pilots. Further, if they had cctv in this jet's cockpit it would only tell you what happened. It would not provide for a solution to the problem during the emergency which is always the priority. There are clear procedures for cockpit management that appear not to have been followed in this incident. Those procedures are explicitly designed to prevent a scenario such as what we are witnessing.
Putting cctv on the aircraft exterior to let the pilots see what is going in areas of the a/c they can't see from the cockpit has been supported. This would give pilots critical information about failures that are difficult to determine in modern airliners. Installing real-time downlinks of the CVR and FDR has been discussed as well - especially after MH370. This would provide investigators with critical information in the event that the CVR and FDR either cannot be found or if the data is unusable.
In the end it is a cost / benefit question. The number of accidents per mile / kilometer flown is incredibly small. You can check statistics to see the many more common ways you are likely to die than from being in a crash of an airliner.
So they wont allow cctv for privacy issues? And yet you walk down any major city street and you are on cctv, you walk in any store you are on cctv. Seems theres one law for airlines and another for everyone else. And yes they would tell you what happened, and then you can try and find a solution afterwards. If as is suggested the door on that flight couldnt be opened, with cctv footage you could see what was the cause of the problem. Was the keypad for entry not working? Had the pilot locked himself in?,etc,etc
Yes I know the statistics, but if one feature could prevent another crash saving 100s of lives isnt that a feature worth having?