Personally, I would love to own and ride a lithium battery based electric scooter (without pedals!). But I would never take them on trails and sidewalks -- 175lbs of plastic and metal is different from a 50lb one. And it doesn't make sense to clump them with electric bicycles since the whole experience of riding one is like a motorcycle rather than a bicycle.

It's often said that the bicycle is the most efficient form of transportation. That's true if you look at the bicycle by itself (it's design, frame, wheels, etc). But if you add the power behind it, an electric motor is actually much more efficient than the human body (sorry, I don't have numbers or references... just my best edumacated guess). So combined with the engine, an electric bicycle is more efficent than a regular bicycle. And in terms of carbon footprint, again, I believe electric bicycles produce less carbon than regular bicycles because it takes a lot of carbon to grow and create the food we eat to power our regular bicycles.

I don't really think there's a lot of in fighting within the electric bicycle community. But there's definitely more clashes with regular bicyclists who often look down upon electric bicycles without even trying them.