This is a great discussion. I think the envrionmental aspect is a worthy inclusion, but it could and should be it's own discussion IMHO.
I DO NOT CARE ABOUT SPEED
Also a worthy point of discussion, and I think it really helps to emphasize that there is something out there for every need, and that lumping "e bikes" into one category is maybe not a good idea. I say this for one reason, every person's needs are going to be different.
Use me as an example. If I were to get an e-bike speed and range would be important for me. Why? There are no bike paths where I live, and very few trails. The ones that do exist are nowhere near me, or go nowhere that I need them to. This means that I have to share the road with cars in an urban and suburban mix. Riding on 40-50mph roads isn't uncommon for me, so being able to remotely keep up with traffic is important.
Range is the other consideration for me. 20-40 mile round trips, if using my bike for commuting duty, is normal. There are not that many e-bikes out there that can support that kind of range comfortably without getting into some very expensive bikes. Even if you account for the extra money I spent, I am maybe $600 in on my Phantom 85 build, bike and all. It can go past 40mph and achieve 40-50 miles of range on a half gallon tank. If that tank gets low... I can simply put more fuel in it, and all I need to do is carry a few ounces of oil with me just in case that need arises.
Somebody made the argument that there is less maintenance in regards to chains and such. Yes, that is technically true, but if you buy quality chains and sprockets the amount of actual maintenance required is very minimal. You should be able to go a few hundred miles before a chain needs proper cleaning and lubrication, and maybe a quick touch-up with the lubrication to prevent rust or dryness if it sat for a while, which is a minute or two of work at worst.
Unfortunately, the cost to practicality ratio with ebikes along with the legal grey areas that can cause headaches for some people, just don't make them a very practical solution for most.
My best example of that is an ebike I have heavily considered getting, the Talaria Sting. New it's $4400. For that price I get a bike that is capable of going 45mph, and has a range of around 40 miles at an average speed of 25mph.
Here is the issue I have with that. Right now I can buy a Lifan built 249cc dual sport motorcycle for $3200. It comes with a 2 year warranty, makes 20hp from an OHC air cooled single with a 6spd transmission. It has a top speed of 75mph and gets over 80mpg. Even if you figure in the cost of tax, title, and registration, I would have to spend another $700 in gasoline before I matched the cost of the Talaria. $700 in gas, even at $5 a gallon means I could ride that bike over 10,000 miles before I spend the same amount of money as I would on just buying the Talaria, and in my State I would have to register it too.