I wouldn't hesitate for a minute to use an electric-assist bike if I needed to for physical reasons. The assist doesn't kick in until the sensor feels the rider applying a lot of pressure, so I doubt it would make anyone lazy. I would hope that people who could keep riding with an e-bike, but might not be able to without one, would try it before they make any decision pro or con.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks