The reason two/three crew airliners which had direct cable control had those controls duplicated and replicated was so that in the event of an external control problem, the muscle power of both pilots could be used to rectify the issue. Having one side feel what the other side was doing through the tactile channel was a side-effect only. Once hydraulic-assist (and eventually all-hydraulic) controls became the norm, there was no fundamental need for one side to mimic the other, as the flight surface deflection was entirely down to the hydraulic systems.
To your first sentence, it was also just how things were done due to mechanical necessity in a two pilot cockpit. As to the last sentence (my bold), ...yet the interlinking remained, surely for some reason.
The presence of force-feedback on the B777's PFCs is in fact the reason that design requires a bypass mode (the oft-discussed "Big Red Button") for safety reasons while the Airbus design does not. The bypass mode exists purely to counter the scenario in which the computer controlling the force-feedback may fail.
That's not quite right, my friend!
The design absolutely requires the handling pilot to be the only one manipulating the controls at any given time.
I will give you, DW, that with the priority switch arrangement, and SOP around it, sure, the overall idea is that of one guy flying the aircraft at a time, but dual input summing makes me agree only if you remove the offending words in bold and replacing with something along the lines of 'encourages.'
