What I don't get is why THE HELL are the two sticks averaged? What's the reasoning behind this? "Hey, one pilot thinks we should descend, the other we should climb, better maintain altitude without telling either one about it". Why?
It seems that it has been known since 1987 that pilots prefer coupled sticks:
In a 1987 evaluation of side stick controllers Summers et al (1987) found that under simulated ‘surprise’ hand overs pilots Cooper Harper rating of the schemes were (in descending order):
Coupled sides sticks with algebraically summed inputs (1.4),
Uncoupled side sticks with algebraically summed inputs and disconnect switch (final A320 implementation) (1.8),
Uncoupled with algebraically summed inputs and priority logic (original A320 implementation) (3.3), and
Uncoupled side sticks with with algebraically summed inputs (3.4).
[...] in the circumstances identified as triggering instinctive responses the value of such alerts is degraded due to the inevitable attentional tunnelling that operators experience in high stress situations.