When a pebble hits underneath my skateboard the reason the skateboard stops and I continue is because ME moving was why the skateboard was moving. In the case of a powered wheel I'll hit the pebble and keep going and keep going, sense the wheel itself is still turning.
I repeat, the wheel is turning, not being turned by inertia and friction.
As for the breaking, I can train myself to lean back when I hit the break, and lean forward when I hit the accelerator. It's not that hard.
PS: I would hope to Jebus that someone would be wearing a helmet and other protective gear with this.
This is correct. Pebbles, cracks, small sticks etc. are not a problem for these boards. I mostly credited the bigger wheels, but as you said it is of course because the wheels are powered. A high enough ledge will stop you dead though (hopefully not literally), I have been sent flying by roadwork a few times. Smaller ledges can be 'jumped' by just shifting weight.
I repeat, the wheel is turning, not being turned by inertia and friction.
As for the breaking, I can train myself to lean back when I hit the break, and lean forward when I hit the accelerator. It's not that hard.
PS: I would hope to Jebus that someone would be wearing a helmet and other protective gear with this.