To take eBikes from a special interest and turn them into a culture would require one big first step, I think people aren't adopting them as fast for practical reasons...
The first step is making eBikes appropriate for mainstream use. So making them super easy to use, super low maintenance/reliable, comfortable, safe, and the tough one: CHEAP. competitively cheap.
Ease of use, and Low cost are the biggest things I think. Currently common bikes and ebikes not noob friendly. Look how the Iphone has done by being noob firendly! eBikes have about 15 things you would have to explain to a noob so they can use it easily and comfortably around town... Usually the things that bug the people who try out my bikes is the locks, lights, and myriad of controls on the handlebar... my emoto came stock with two different power switches! one on the battery and one on the handle bar, then you another button for it to give full power... this sort of design has to stop!
so things needed:
-Dutch style frame locks that don't release the key until locked (for ease, security) takes several steps out of locking, much quicker, makes quick stops more viable. Obviously you would need another lock stored on the bike for night time or parking over a couple hours or in quiet areas. Ideally there would be a remote or proximity activated security system with alarm and remotely actuated wheel/frame lock and for the chain as well if you live in Detroit. The closest I've seen to this is an ABUS moto chain with motion sensing lock.
-Automatic permanent 24/7 blinky lights (for: ease, safety, peace of mind) The front blink is the single most important thing to safety, most accidents happen in the absence of a front blinky light. Automatic to insure they are always on, so you don't have two more buttons to press every time you mount or dismount. (ive already glued mine to the handlebars/mounts) I wrote Peace of mind above but that was a trick... peace of mind is not something you want, it will lower your alertness and thus you'll be more prone to crashing. Its the problem with bicycle helmets which also happen to be ineffective in accidents above ~12mph, buy moto helmets if you already use a front blinky light 24/7. I've read there was a new type of bicycle helmet: Abus Cranium.
-Seat height adjustment simplified, my guest riders can need really different seat heights, group riding sessions have been saved by having a 20" folding bike for the short riders... unfortunately I've removed all the Quick Releases so the seats don't get stolen... So I need something that will attach the seat to the bike so I can put a QR back on. Another thing that might require some innovation is something to fix the rotation of the seatpost and allow only up down adjustment... this makes it much quicker and easier.
-handle bar controls simplified... I think I'll do this to my bikes now: I will label the rear brake as Turn, and the front brake as Straight, then noobs won't drop the bike when they try to use the front brake hard in a turn. All noobs should really be made to practice emergency braking to an external que. Another thing is Standards: I follow the moto brake lever standard as its much more prevalent in the world. Left is rear brake. Other controls need to be automatic or simplified... I'm happy I don't have to shift gears anymore, deraileurs add complication. I'd like A type of brake that didn't need adjusting as the brake pads wear.
-Flat free and a bike free of frequent cleaning and oiling of the chain. One of my eBikes currently has a tire made of foam, no air, it seems like the way to go for casual riding so I intend to swap all the rear tires to foam - airless tires. Slime helps a bit, but eventually you'll forget to re-inflate your rear tire every month, or because of parking situation or something it won't be convenient to re inflate often... Then you'll hit a hole or curb and go flat - the most annoying thing ever, esp for noobs and many bikers. Hub motors are great because you don't have to use your chain drive much anymore, you still have to lube occasionally so the chain doesn't rust so i use "clean ride" which says you can reapply it without having to clean the chain.
-A Low step full suspension frame, and comfortable saddles that don't look awkward. I think a Low-Step FS frame (similar to scooters) would be the ultimate in comfort and convenience. Some noobs aren't sure how to first mount a bike, its another step for a guest ebiker that is going for a ride... eBikes need to take some ques from the most common 2wheel culture in the world - scooters. A lot of random people who tend to influence other people look at bicycle saddles and think ew - it supports/touches our junk and the parts of us thats right next to our junk... This is notion and awkwardness is probably spread more by naked bike rallys. I think the A2B metro (now Octave) was on to something with its scooter style saddle/seat, they have since narrowed the front of the saddle to allow lots of pedaling but for most it was fine, like most future ebikers will pedal their nuts off anyway. Ideally I guess you would want something that can morph between a seat and a saddle...
There is more to add but its getting close to sleepy time here