IMHO Drunkskunk has hit it on the head. Take the rocket science out of the appearance, use Ypedals design idea of frame enclosed (but accessible) batteries and make it reliable with a BIG seat.
Unfortunately, again IMHO, I don't think there is enough demand out there today to justify the creation and distribution of such a beast. A brief visit to http://largoscooters.com/electricbikes.html
will show you a few excellent designs that accomplish most goals of price, comfort, stealth and dependability. These are bikes that are already created, ready to ship and are probably selling in limited quantities over the internet.
Were the demand there I believe we would be seeing these in LBS's, Big Box Stores and on our local streets and bike paths. As it is, in my community which is a city of over 50,000, I have seen ONE electric bike besides my own in 13 years. Plus I live in Florida, land of flat streets, excellent bike paths, sidewalks, bike lanes on roadways, six weeks of a mild winter and a hill is a bridge.
My bike will, on occasion, generate a question or two but only one person has asked me where to get one and when I told them how much it cost the light was going out of their eyes. That person however has a personal grudge against paying bridge tolls and may buy one just to beat paying a two dollar toll every day. (no tolls for bikes)
Sorry, didn't mean to be negative. Plus I do believe great marketing, a great reasonably priced dependable product with a 20 mile, 20 MPH range, would succeed if it were backed up by local service. Until then I also believe most EBikes will be sold over the internet to folks like us who seek them out and want to learn as well as ride.
Do your own man on the street interviews and ask your friends what the difference is between a volt and an amp. Ask them how much gas would have to go up in order for them to give up their cars or motorcycles to ride a ebike. I don't think you'll like the answers.