I agree that bicycles are a superior ride in every way, but a large number of people who don't use bikes do use scooters, and that's enough to make me a fan of them.

Also, speaking as someone who rides a pretty vanilla road bike, the rental e-bikes feel bizarre to me. You call scooters "grotesque" and "suboptimal," but have you ever tried a Jump bike? I can't put my finger on why, but after renting them a few times out of curiosity, I now find myself walking past them and going an extra block to find a scooter if necessary. I prefer my own bicycle over either rental option, but I think rental e-bikes will have to get a lot better before they become as popular as rental scooters. And even my bike doesn't win in all categories. Both rental options (and scooters especially) have an advantage in parking quickly and worry-free at my destination.

In any case, I'm happy to see a variety of options available. I hope rental scooters don't disappear until they are replaced by a better alternative that captures what is attractive about them.