Battery range is the issue. The same as electric cars. I've thought it might be cool to have an electric assist bike that you could use to tour but unless you just want to use it for help now and then, like on the big hills, you'll run out of juice.

I've seen some really nice looking recumbent trikes that have solar panels that run the electric assist, no battery. So if it's cloudy you just pedal. That could work and would eliminate the hassle of battery charging.