HundredPercentPlease: There are improvements that can be made in every machine when new levels of human ineffectiveness are explored. But the "non-linked sidestick" seems to be of significant issue only to those who don't actually fly the Airbus.
It might be a tiny bit better if it had interlinked sticks. Maybe. So long as new issues are not introduced - and I'd bet they would be. Dual independent electric gives a level of redundancy that everyone conveniently forgets.
It might be a tiny bit better if it had moving t/l.
It would be a bit better if the "dual input" and "stall stall" could live side by side with each other.
But none of that matters, when you have pilots who exist in a system where it is fine to pull CB's on a critical flight control system when in flight. Pilots whose training and experience leads to a Pavlovian response of pulling up in the face of undiagnosed adversity. Pilots whose communications are so bad that instructions like "pull down" are given.
To change the aircraft is to accept that the level of piloting is fine and that it's simply the machine that needs fixing. Never has there been an accident where this is so far from the truth. The machine was airworthy and safe, the pilots were not.
The fault lies in the training, standards and culture that the pilots were exposed to. I would bet that the same individuals with different training, standards and culture would have:
Not caused the fault in the first place.
Not over reacted to the yaw.
Not flown a zoom climb all the way to a stall.
If they had done the above, used SOPs to allow the more experienced pilot to assure control and fly a successful stall recovery (by simply lowering the nose).
If I want to see what the FO is doing with his sidestick (for example, while I am pressing the button during a baulked landing where I have taken control, or even just on a normal approach), I use my eyes. They still work quite well, and give a full picture not just of what inputs the FO is giving, but what his face looks like too - which cannot be replicated by any control column system that I used to operate.
This is all about training (and the cost of doing it properly).
Do you really think that there is any reasonably intelligent person on the planet who would not think to look at the FO's sidestick? Do you really think that normally functioning human beings when confronted with their own death and the death of several hundred passengers, if they were thinking calmly, would sit back and rely on casual assumptions. You are underestimating the impact of acute stress on human behaviour. When the Qantas A380 had the engine failure the pilots involved made it very clear that having a large number of highly trained pilots available in the cockpit was a major factor in successfully handling the incident. Just getting through the ECAM messages was a major task.
I'm not arguing that there should not be investment in training. But it's not a choice of one or other of the two factors. I don't argue with the obvious errors that resulted in the abnormal conditions in the first place, but I do see strong evidence that confusion escalates quickly and the design philosophy only makes that worse.