I’m not sure the bike is the accurate comparison target compared to the scooter or car for commuting. Also, I think the main reason they are not so popular is laws. I think there was another article on solar.lowtechmagazine where this was discussed, but from my fuzzy memory, the issue there is not yet a separate category for these kinds of high speed limit, electrical assistance vehicles. You either have to use it like a bike, in which case in many countries you are not allowed to go past a low set speed limit (something like 30 km/h) with elecrical assistance, or you have to register the vehicle to be in the category of motorbikes, in which case you are subject to the same rules, like having a license plate, needing to get your vehicle checked at the garage every year and other things. Maybe try to find the article, it will be better explained.
Well, unsafe if there are cars all around you. But if we replaced a lot of cars with these vehicles which typically go around 40 to 70 km/h cruise speed, I think it would become way safer than cars.