Scooters are accessible to even the grommest of groms - they are very big in my kids circle of friends. I am conducting an ongoing psych-warfare campaign to get them on boards, but it's not gaining traction.
Worst thing is a proper park scooter, welded everything, heavy as fook, spins round on super smooth headset bearings and **** you in the shins when you move it out of the way.
Park scooter? Obvious, I s'pose, but first I've heard of those.
I think the popularity of scoots is like you say, even the clumsiest of grommets can ride the things, they're easy to fold away, and they're faster than walking.
One thing I can't get my head around is the popularity of those tiny little wheels that boards have on them now. It was bad enough when I had blue Kryptonics and Bones on my boards, hitting gravel and pavement imperfections stopped it dead in its tracks, those tiddly little wheels must get stopped by the tiniest litte things.
Still, boards are much lighter and more flexible now, so perhaps that helps; my old Hobie is a real plank!