Eh - I've fallen off a bike twice at relatively low speeds, and both time I've broken a bone (first time a finger, second time a scaphoid fracture).

I think it's important not to under-react just because the speeds are lower than a motorcycle - all those bones in our limbs break just as well at 10mph. When on a bike or a scooter, scaphoid wrist protection and at least a jacket on at all times, for me.