At this point, battery technology is limiting EVs. They're fairly heavy and relatively slow to refill. But 80% quick charges and improving technology are making things better as we speak.
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That's why I bought an EV with a built-in ICE generator.)
EVs do have different performance characteristics. The Volt has a ton of torque and no transmission full of gears to shift through. Accelerating seems faster than it is, due to the torque and lack of jerking at gear changes - it just goes when you push the long skinny pedal. The Volt's battery pack layout gives it a low center of gravity. For a 3800lb golf cart, it actually seems quite quick and nimble.
Changing to an electric drivetrain on a bike also gives you some room to move things around and possibly redesign things to work a little better. I suspect most early models will be like the one rumored here, dropped into an existing bike with as few changes as possible. It keeps costs down, and is easier for the public to accept. But once people are used to the idea and things are more affordable, it opens up the path for some radical changes that we don't even think about today (like having the motor on the swingarm, completely eliminating most chain issues). Just like all the maintenance that you simply don't need to do any more, limitations of the ICE setup will simply cease to exist.
Things are far from perfect, but I'm excited about the future possibilities.