Suicidal motorbikes are allowed with license and insurance though. Not saying that's optimal for public safety, but that's a big distinction.
I think that's the logical line between e-bikes an electric motos: at what power or speed do you want to start requiring some kind of licensing or insurance?
Yeah licensing and plates would be interesting. Although an e-bike is lighter than a scooter and will make less damage to the other person, the driver weight is probably signifiant too.
Not sure how that works in the US but in France (and probably Europe?) everyone supposed to get a "civil responsibility insurance" that will cover many thinks including accidents on non-insured (legal) vehicle.