Manufacturers must design for the lowest common denominator.
MCAS breaks this rule.
Either you ground MAX now or you hand back control to the pilot and hope that
the aerodynamicists concerns over reduced static margin dont result in another smoking hole.
Stick input (the only resort along with opposing trim that a pilot suffering from startle factor turns to when faced with loss of pitch control ) must override MCAS.Once overriden,it must not return for 5/10 seconds giving the pilot time to think.MCAS must not oppose stick input.The aerodynamicists will of course say this totally negates the design intention of MCAS.But a pilot,even a sub standard one,will surely know if he/she is facing a
real stall or a faulty sensor.So let the pilot decide whether to respect MCAS or not.
Secondly,the pilot needs a shaker inhibit switch right there on the stick.Other manufacturers provide this(Fokker/ERJ).For the MCAS-installed
MAX its an absolute must simply because the shaker can mask MCAS activation..But its a great design feature for any commercial airliner.
Boeings AD in November was clear and unambiguous and in a perfect world that would be the end of the matter.But it disregarded
the effect of the shaker and startle factor on cognitive functions.Startle factor disables cognitive functions.Once the pilot has cancelled the shaker and is assured of pitch control of his/her aircraft,cognitive functions will kick in again.
A highly-proficient crew,having read the Lionair report and Boeings AD,would not even retract flaps but remain in the circuit and land.You
dont design for the best crews though,you design for the mere mortals.