I mean, what choice, besides averaging, would make sense? Completely disregarding one pilots input seems worse, and averaging is what happens in a mechanically connected system. The crucial difference is that in that case the pilots can feel that this is happening. I don't know what sort of force feedback the Airbus sidesticks provide, but this lack of feedback seems to me to be the real root of the problem, not the averaging itself.
Disregarding one pilot input seems better: one pilot can correctly fly the plane while the other does nothing vs two pilots getting confused and flying planes into the ground. Even better would be a system that somehow follows the "I have the stick" procedure, although I don't know if that is possible.
You are right though that either way force feedback make sense. You could even just do a buzzing if there's dual inputs, like when you take your hand off a lane-controlled vehicle.
Say one of the pilots is suicidal, or had a heart attack and is unconsciously while holding the stick in the wrong direction, how does the airplane know which input to ignore?
