Are you saying that after Autopilot/Autothrottle failure at altitude you accept pilots are unable to control the aircraft.
Pilots should be able to hand fly his aircraft at any altitude in emergencies such as mentioned. On the Boeings I flew we had a set of memory power and attitudes which we would fly in the event of asi indication failure for example.
In the examples mentioned crews lacked the handling skills to manually fly the aircraft to lower levels where the emergency could be dealt with.
I repeat in the Air Asia example, the crew had a perfectly flyable aircraft in Alternate Law i.e. handling like a non fly by wire aircraft. The only things missing, an autopilot and auto throttle?