I admit that this is no more than a WAG! My WAG is that those who hand-fly frequently probably appreciate the visual ques and physical movement of the levers. Those who do not hand-fly frequently are probably relying on graphic displays to report thrust details, rather than lever position. While firm SOPs 'may' help, every pilot has his or her own routine for scanning and obtaining important information during 'critical phases' of flight. As long as s/he obtains the information from a
reliable source, does it matter which source is used?
I'm old, grey and very used to pushing/pulling multiple levers, must of which have friction adjustments. If I noticed an un-commanded change of any lever's position, I think I'd test it a little bit, reset it as necessary and tighten the friction lock.
(FBW, including auto-thrust) is not for me. It is perfectly OK for our grand-kids, but only if they fully understand exactly how every component works and interacts with every other. Some do - and some do not.) And please forgive the rant.
