ccp6f
While I appreciate your effort at outlining some base scenarios, you mixed in a bit of hyperbole with a premise and conclusion there.
(c) The autopilot is unstable (in severe turbulence) with loss of airspeed data and caused the plane to stall. Had the pilots been in direct control of the aircraft the entire time, this would not have happened. This is corroborated by the incident on Quantas flight 72. Thus the flight control system is poorly designed and should be made more robust or the FBW idea should be scrapped altogether. This would be catastrophic for Airbus.
Your bit in italics seems to me a false dichotomy. FBW is a design practice that is used (successfully) throughout much of aviation - see for example high performance Military Jets since the F-16 or so.
If the Flight Control System in this, and or other Airbus designs (by which I assume you mean all other than the flight control surfaces themselves) could use an improvement, revision, or correction, why do you bring up "scrapped altogether" as an OR statement? That's a non-option, not only due to its risk to Airbus and its business base. Continually tweaking and correcting this, that, or the other is how the aviation business has been operating for some decades. Small improvements here and there, sometimes triggered by tragic events such as AF 447 ...
FBW is an industry standard that works well enough, regardless of my own or others' discomfort with some of its drawbacks.
From the early pages in this thread, a non-trivial amount of discussion has addressed the point that points to pilots having to fly/act when the auto functions degrade or change mode, for one reason or another. That doesn't mean that FBW needs to be scrapped, but it does require any professional aviator to know his aircraft systems inside and out, and to be familiar with degraded modes for any aircraft system or sub system.
Any pilot is going to be challenged if, quite suddenly, airspeed indication becomes unreliable. It's a key piece of information that is the foundation of any flying decision or action a pilot undertakes.