Like car services, scooters are a great complement to commuting on public transit. Most of the time, when you commute on public transit, you don't need another vehicle. But things come up unpredictably that require you to run a quick errand or go somewhere outside walking distance to meet friends.
When I ask people if they would commute to work on public transit, the biggest thing they worry about is, "What if I have to ____?" They don't like the thought of being useless when their partner asks them to run an errand, or left out when their friends plan something after work. Even if 95% of their workdays would be nothing but catching the bus or train downtown, working and patronizing businesses in a small walkable area, and then taking the bus or train home again, and even if it's significantly less burdensome than driving, a lot of people will still drive because they can't give up the feeling of being able to deal with contingencies. Rental and on-demand transportation options address that without forcing people to keep their own vehicle on hand every day even though they rarely need it.
I think this is an important factor for making public transit attractive to people who are accustomed to the advantages of driving everywhere. Right now, car-based services like Uber and Lyft are sufficient for that, but as city centers back away from the massive accommodations they've made for car traffic, bikes and scooters will become more important.