Why has pavement personal powered transportation not taken off?

There is a niche, somewhere in between cycling and motorcycles/mopeds for personal powered transportation that can go on the pavement. The niche is people who commute less than 5 miles, but too far to walk (greater than 2 miles for most people), who don't want to get sweaty cycling, or get killed on the roads on a motorcycle/moped. Segways are in this niche, but are not the optimum, as the commuter cannot store them under their desk at work. The other contenders are electric skateboards and motorized scooters (a kick scooter with a motor), and the smaller versions of these are easy to store under a desk.

So what are the barriers to this niche being exploited? Legal - road and pavement legality? Image - not cool enough, or too youth-oriented for the commuter? Practicality - concerns over crowed pavements, pedestrians getting annoyed?