These have things in common too: wheels, pedals (remember, they're only pedal ASSIST), dirt tyres etc. You've just made an arbitrary decision as to what is, and isn't, a core principle of riding. Downhillers use shuttle vehicles and chairlifts to get to the top of the hill, and that's all artificial power, no pedalling at all.
I'd probably agree that it's not 'cycling' in the purest sense, but so what? Nobody's forcing anyone to give up their normal MTBs and ride one of these, so why all the hate towards something new, just because it challenges what you accept as the norm?
Maybe there could be issues with trail usage down the track, if electric bikes became very powerful and very common, or maybe there will be no conflict at all and everything will be sweet. Maybe the technology that evolves from these will give birth to awesome little electric motors that you can carry with you as an emergency backup in case you suffer an injury in the middle of nowhere and are stuggling to pedal home. Maybe we'll end up with drive systems that enable people with disabilities to experience our sport where they previously couldn't have. Or maybe they'll just remain a fringe novelty and never really take off.
The point is that none of us really know how this concept could play out, but dismissing something that hasn't had a chance to prove itself either way is pretty close minded.
