The thing with those guys, as you have rightly pointed out is for all their problems they do get out of the way and filter through traffic (dangerously as you point out)

A single startup with cooler sized robots tottering down the sidewalk is fine. When every single delivery company gets on board then we have a shit load of those things kicking around and in the way. I have the same issues in cities with those scooters that get left all over the place.