I think there needs to be a distinction made between motor-assisted bicycles (regular bicycles with a low-powered hub motor) and those contraptions that are clearly an electric scooter with barely-functional pedals attached. I saw one a while ago that had pedals so far apart as to be unusable, and the rider was clearly using the motor as the primary means of propulsion.
This is what I mean:
This sort of thing is a power-assisted bicycle (as long as the electric power isn't too great)
This is not.
The former type of bicycle have fairly sensible reasons for their existence- such as some people who physically can't ride a normal bicycle for long distances etc. The latter, imho, exist solely to avoid having to license, tax and insure a motorcycle.