They're heavy and expensive and require more maintenance than regular bikes. For many cities, riding at 35 km/h on average also sounds pretty dangerous.
A range of 72 km seems excessive, too. That's a 2-hour ride, which sounds like something you'd do as a leisure activity rather than on an everyday basis.
That said, I'm quite bullish on the future of bikes as a mode of transport in general.
> They're heavy and expensive and require more maintenance than regular bikes. For many cities, riding at 35 km/h on average also sounds pretty dangerous.
Most e-bikes with 250W engines are capped at 25 km/h so, essentially, for a fit cyclist they only help for uphill climbs and acceleration. But even 25 km/h is good because it means you can keep up with more traffic and thus ride on heaver trafficked roads.
I agree that e-bikes aren't that amazing in good weather, but they are very practical in cold, snow, and rain. A 250W engine makes a huge difference when its snowing and you have a 12 km ride home.
Ebikes require a bit more maintenance than a regular bike for sure, but a lot less than a car. They also let you transport more cargo than a regular bike and very often get you there quicker than a car.
I also know a couple people who own ebikes and use them exclusively for running errands (e.g because they don't want to break a sweat when getting groceries).