It's not common, but it does make sense to do! No, not in charging the battery but in braking. Regen slows down the bike without wearing down your brake pads, which is extra important with a heavy bike. I cannot even manage 900 miles without changing my longtail's pads. I have yet to replace the pads on my regenerating e-trike.
The extra 20% range is nice but I'm more happy about the money and hassle I've saved in not replacing brake pads.
When cars are the only way to get to a bar or a friend's place, then you're going to get drunk drivers. Car dependency has a big hand in causing these deaths.