It may seem unnecessary or over-engineered to have 9 speeds on a bike, but it’s not going to negatively affect anyone here. There is something to be said for optimization, and nine gears allow you to compensate in real time between the throttle and changing gears. You’ll really appreciate the extra gears when it comes to climbing hills. Lowering your gear allows you to maximize your leverage and make it up the hill with less effort, on yourself and on the electric motor.