It's notoriously hard/expensive to get a car/standard bike parking space. Even at home, and probably wherever you go if the place has any popularity. Think about parking car in Shibuya.
So a small vehicle has a real intrinsic value, not as simple as a parking a bicycle, but pretty close.
PS: Honda also makes the Monkey, which is ultra cute and pretty popular
I think I've seen that Honda one around NYC. Had no clue what it was. It just looked like someone was riding a brief case and that's basically indeed what it is.
- https://en.wikipedia.org/wiki/Honda_Motocompo in 1980s and
- https://motocompacto.honda.com just a few years ago. This one is electric.