I work in a bike shop, and we sell ebikes at the cheaper end of the scale, which leads to two big problems that make me hate them.
1. Unrealistic expectations
A lot of people expect more from the assistance. They equate speed with power, which is ridiculous. They also get beyond the 15.5mph legal threshold and complain that the bike feels heavy and slow, which of course it will, as the battery and motor is heavy, and if it's a wheel mounted motor will have friction when not powered. Some people even think they are getting something equivalent to a moped or motorbike for a fraction of the price and with no registration, licence or insurance. I am quick to disabuse them of this notion. Different types of ebike have their place, as you all have described above, but a lot of people who come to me wanting ebikes would actually be better off with a lightweight £500ish hybrid that would offer a better cycling experience.
2. Cheap ebikes have their place (like cheap regular bikes have their place), but people think a £1000 ebike (or less even) is the same as a £3000 (or more) ebike. People subject cheap ebikes to heavy, sustained use and are then disappointed when they fail, because in their mind £1000 is an expensive bicycle (relative to a 'normal' bike). I get people buying these cheap offerings and doing Deliveroo/Uber eats etc on them. That's not what they were designed for, and yet people end up disappointed, no matter how good the explanation I give them is, both before and after purchase.
I must stress that the above pertains only to the market I operate in, not the higher quality ebikes and those riders that know what they're buying and how to use it properly. Sadly though, due to the accessible price point, I think the overworked cheap ebike makes up a large chunk of the market.
For what it's worth as well, I'd like to see the speed cap lifted to 20-25mph, as I think a lot of cyclists can attain that sort of speed anyway, so it's not like cyclists are going to be zooming around much faster than they were before. This would stop so much disappointment and make the ebike more useful to more people, without being excessively dangerous or giving rise to a nation of hoodlums.