As a kid I knew a scout leader who was a pilot. He took me up in his Pipe[r] Cub (or similar) for a brief jaunt around the airport, but I don't recall handling the controls (if that were even possible). It was a weird sensation, being so close to being exposed (just a thin skin of aluminum...).
If you have two people operating the same controls, there's a problem. That's why "my airplane" is vital.
The only example that MM can point to where the non-coupled sticks in an Airbus was an issue (AFAIK) was the
Air France 447:
In a July 2012 CBS report, Sullenberger suggested that the design of the Airbus cockpit might have been a factor in the accident. The flight controls are not linked between the two pilot seats, and Robert, the left seat pilot who believed he had taken over control of the plane, was not aware that Bonin had continued to hold the stick back, which overrode Robert's own control.[237][238]
Reference 238 says:
"CBS News aviation and safety expert Captain Chesley "Sully" Sullenberger explained that he believes that the disappearance would have been less likely to have happened if the plane had been a Boeing instead of an Airbus. This is because the control wheels [in the Boeing] are larger and more obvious. Sullenberger showed CBS News correspondent Mark Strassmann the difference with an Airbus simulator. There's a small movement on the Airbus flight controls called a sidestick, which raises the nose of the plane and instructs it to climb. Pilots rarely perform the maneuver at high altitudes because it can be very dangerous, but that is exactly what the pilot of Flight 447 did."
(Emphasis added.)
If you have two pilots manipulating the stick/yoke, you're doing it wrong. No matter how the two yokes are designed. Robert should have said, and meant, "my airplane".
And a pilot who pulls back on the stick/yoke at high altitude is doing it wrong. Having coupled controls wouldn't have prevented him from doing so.
IOW, the problem isn't the design of the plane, it's the training and communications of the pilots. Yes, of course, one can try to design around mistakes and miscommunications like these, but it's not going to fix the underlying problem. The money spent on hardware would be better spent on training and evaluation and implementing best-practices.
IMHO.
Cheers,
Scott.