Chris your argument for a dedicated AoA display makes several assumptions.
First that attitude is proportional to the indicated AoA; this might not be true for large values, or a range of configurations, wt, cg, and in this instance gross mis trim.
Might there be a difference between a recovery using the alpha gauge only (military pilots?) vs the AoA value having to be interpreted to cue an attitude change; the latter being important re roll attitude.
Second, it is assumed that the crew will 'see' the indicator, comprehend its meaning, and act accordingly. EFIS aircraft already have forms of AoA displays, e.g. min speed and barbers pole, providing the ASI is working. Any new display could add workload in an emergency situation.
Where new displays have been introduced to minimise risk after a primary system failure; they are located in similar (logical) task related positions as those in normal operation.
A key aspect in this and similar accidents is that crews were apparently unaware of the situation and 'puzzled' by indications and cues already available; thus an important quality of any new display / warning is to trigger a change in perception, together with high quality information, - not necessarily about what is happening, but what to do.
This is a demanding design task, particularly as in the 'highlight' accidents, the crews put the aircraft into the stall, thus there was a strong belief that their awareness and actions were correct.
Also, with the thread continuing focus on recovering from an extreme situation, the problems of awareness preceding the event and methods of stall avoidance are being overlooked. How did the crews get into these situations, what was the basis of their awareness.
This accident involved a complex interaction and degradation of several systems, hence the concepts of BUSS and FPV using existing display location for 'failure' conditions, which appear to be have been chosen to provided a degree of normality for stall avoidance and recovery, not an extreme 'one off' accident.
A further area for consideration is whether protected aircraft generate crew dependance on the protections, vs indicators and crew action for non protected aircraft; which crew would have the better awareness. If this is the case then crews in protected could suffer the greater surprise, adding complexity and difficulty in comprehending the situation when the protections degrade.