I commute every day on an ebike, mostly on roads but some cycle paths. ~15mph safely on an urban cycle path requires a much higher level of skill than many commuter cyclists have.
I’m used to driving, riding a 50cc scooter, riding a horse and mountain biking, so I’d say that I have a better awareness of both the observation and judgment side of riding, as well as bike handling skills. Plus my bike has big tyres, big brakes and lots of suspension travel – overkill for commuting but it does mean it’ll stop a damn sight quicker than any short wheelbase, high saddled, skinny tyred bike.
The thought of less experienced or complete beginner cyclists being able to legally whizz around town at ~20mph or more seriously worries me. 15mph is more than fast enough. If you want to go faster you can pedal harder or use gravity – I do both but at least a bike going fast downhill is not unexpected. The amount of illegal ebike use is bad enough!