When you look at the top end of the market, an (un)fair margin has already been added, and yet you don't seem to get much support. "Sorry sir/ madam, we'll have to send it back to the factory for repair"....
I see the point you're making, but that seems to relate mostly to premium mid-motored e-bikes. Granted, local bike-shop knowledge on "electrics" is sadly lacking beyond "replace the motor, replace the controller, replace the display, replace the battery", but is that the fault of the dealer? Bosch certainly insist on a return to factory policy not only for e-bike motors, but also their professional power tools (as another example). I'm told they do that to understand where the problems are and likely causes "for future product development". Yes, it's a great inconvenience, but if you don't like that policy don't buy their products. So I don't.
The biggest problem, as I see it, is that bikes with problems just get dumped. Selling the idea of e-bikes as a green measure, then seeing untold numbers dumped, scrapped, well before their potential lives undermines all that justification.
Are they really all dumped though? The problem is most likely caused by people like me with mid-drive e-bikes, where the motors employed will become obsolete very quickly, and the frames then useless (although could be stripped of other useful parts). Maybe there's a future industry in someone grinding off the obsolete motor mounting brackets, welding on new ones that fit new motor models, and refinishing the frame?
My local Council certainly retrieves all "cast-off" bikes and containerises them at the local tidy tip for collection by Charity bike shops. The Charities salvage re-usable parts and put most of those bikes back into service for those who cannot otherwise afford to buy one. The bikes get a second lease of life, provide jobs/training, and provide a useful asset to those most in need. Not sure how many other Councils do that though.