I think the only way it really could have been revolutionary is if it were faster, smaller, lighter, and safer (both for riders and for people around them) at o

I think the only way it really could have been revolutionary is if it were faster, smaller, lighter, and safer (both for riders and for people around them) at once. Think of something that doesn't measurably increase a human's form factor, slows to human speeds when around walkers but can go much faster otherwise, packs down to be easily carried, etc. Then you'd have the use case where an individual person could take walkways for car-commute distances. But since that wasn't possible, it ended up being a worst-of-many worlds kind of device - too unsafe (for riders) for roads, too unsafe (for pedestrians) for sidewalks, too slow (in practice) for its cost, too expensive for its benefits, too heavy, etc, etc.