Scooters are much smaller than bikes. You can easily take them with you in an elevator: Put it under your desk at work, store it at home. Scooters mostly drive by themselves, e-bikes need paddling. Less maintenance, less moving parts.
I'd also note, on "security, acceleration, deceleration, max speed"
Security is really the same as any bike, though it's much harder to steal the wheels!
On acceleration & max speed, obviously it depends on the particular scoot, but mine is much better than a typical human on a bike. That's a Ninebot Max, costing about £600 ish
Yes. The budget starts at 1000EUR vs 250EUR. The difference is much less once you realize that you probably want two (disc?) breaks, probably suspension, larger wheel size. When I was making the purchase it was basically same price at that point.
Yes. It takes a few hours to learn to ride an EUC. But I'd wager that EUCs are safer because of that. Most accidents on rental scooters happen to first-time/occasional users. The fact that you need to learn how to ride an EUC gives you an appreciation of how bad things can go if you push farther than your skill allows.
In the end, EUCs are safer (larger wheel doesn't get locked in small potholes), more comfortable even without suspension, break faster due to more powerful motor, and are more compact.
Probably depends on the scooter. The segway ones I've ridden sound like plasticky junk and feel like it. The original bird scooters, on the other hand, are luxurious. They are xiaomi 365s. No suspension but it didn't bother me on this scooter with the ample tires. The brakes were great. If I'm able to lock the wheels while braking, that means the brakes are stronger than the grip of rubber to road, and the only way to get better braking is stickier rubber or an ABS system. A bigger motor wouldn't help here since the brakes already overpower the tires.
I would say durable rather than luxurious. The breaks were, but I'd say the tires weren't. I am yet to experience something like this on my v8f. There are other advantages of larger motors, like ability to ride uphill at larger inclines. Scooters are easily overpowered there and essentially useless in more hilly places. Bottom line is, that I am yet to meet a person who tried an EUC and prefers a scooter.
It's an incomparable experience.