@flix123 You are a little too optimistic that there should be plenty of torque at low speed to balance the rider. Nose dives are possible at any speed, including from rest. A common nose dive scenario is a rider trying to cross an intersection quickly and nose dives as a result, long before they accelerate to high speed. Or going up very steep hills at moderate speeds.
A warning sign of an impending nose dive is a "surge", which feels like a very momentary wheel slip. If you feel that, back off immediately because a nose dive is about to happen if you keep accelerating. It is most noticeable for heavier riders going up steep hills or accelerating hard. Not noticeable at high speed, which is why heeding pushback is critical if you don't know what you're doing.
For the record, I am a 230 lb rider with 190 miles on a +XR. Obviously I am still learning, and I have never pushed beyond pushback speeds. No high speed falls (or even medium speed falls) so far. I do have Fangs and they have touched down 3 times or so, all at relatively low speed.
Edit: It is impossible for FM to eliminate nose dives because no matter what they do, the rider will always be able to force it to nose dive. However, I think there are steps that FM could do to help riders from unintentionally pushing their boards into nose dives. Maybe they are worried about liability, since if they leave it up to the rider they can't get in trouble for implementing an imperfect solution.