Interesting, I hadn't thought about those aspects of it. Personally, I don't have much desire to put an electric kit on my bike now as it is.. just thought this was an interesting product. I enjoy the workout my ride to work gives me and having help would most likely decrease my desire to ride on most days.
I found quite the opposite - an electric bike made a bike radically more useful, year round, when I was commuting in Seattle. I don't ride ebikes now mostly because I work from home (technically, a separate office on my property), and I live on a 55mph rural road. Also, none of them are actually together and working, and I need to finish up a higher speed R&D build at some point.
But commuting daily, an ebike was easier than driving. If I wanted a workout on the way home, I simply didn't turn the assist on. The big thing it solved, for me, was arriving at work sweaty. If it was warm, I'd be sweaty. If it was cold, I'd be OK, but if I had rain gear on, well, I'd just sweat from the inside out. Having a motor solved that nicely, and the higher speed made it a useful car replacement for an awful lot of stuff I wouldn't have taken a pure bike on (climbing a steep hill with a hiking backpack full of a large grocery run isn't fun on a regular bike, but not a big deal with the assist).
If you've got the bike thing going already, great - no reason to add a motor. But it turns a bike into a car, in most urban areas. A friend's family has an electric cargo bike, and his wife rides around with three kids and groceries in it all the time (she's a tiny woman, maybe 110lb soaking wet). It opens up a lot of options for her to take them out, and she can get a few hundred pounds of kid and grocery up Seattle's hills at a useful pace.
But, as Ocelot notes, if you're going to do it, do it right. And I have the firm opinion that a "wheel" style ebike is never the right way to do it.
