Everyone I know who has ridden a dockless rentable electric scooter has absolutely loved them. I've used them to commute to/from work (what would normally be a 20 minute walk turns into <10 minutes if I'm in a rush), quickly return home from ~3 miles away after running into Golden Gate Park (too sweaty for a Lyft), and running errands to destinations a bit out of walking distance during rush hour when public transit/Lyft would be painfully slow. The added benefit is that the scootering was more fun and less or comparably expensive to the alternatives.

Scooters have advantages over bikes as well for this type of usage. It is far easier to switch to pedestrian mode (i.e. walking next to the scooter) when you need to navigate a crowded cross walk or slow down suddenly and get up on the sidewalk when an aggressive taxi/Lyft/bus stops short in front of you or turns across you. Your center of gravity is lower than on a bike lessening the impact from falls in some cases.

The parking debate seems pretty bimodal and has been debated seemingly endlessly already...

The safety concerns complaint is interesting. Lots of bikers already ride without helmets but no one seems to care/complain about them too much. Lots of complaints about safety riding on the sidewalks, but I haven't seen much hard evidence that collisions are actually happening en masse.

A 10-15 mph cap in SF seems totaly fine for what is meant to be a casual, relatively short distance means of travel.

How are you concluding that the economics are mediocre?