I have seen thousands of wheelchair users. I have never seen a car that i) would have been stopped by a kerb and ii) would not have been stopped by a ramp.
Your point illustrates the subject line nicely. Very many people have a disability, yet you're suggesting very rare benefits of keeping kerbs that hamper people with disabilities.
Bear in mind that, if that really happens, it is a much, much less frequent occurrence than people being aided by the dropped kerbs and not stumbling/falling with pushchairs, wheelchairs or unsteady feet when mounting full height curbs . The proper fix for that also isn't making kerbs full height again.
In most cases you're more likely to be hit by a car if you're riding on the sidewalk. Last numbers I suggest that your risk of being killed by a car is about twice as high when you're on the sidewalk.
The reason is simple: Bikes move quickly, and bikes on the sidewalk are much harder for motorists to see than bikes on the street. That makes it extremely difficult - sometimes impossible - for drivers to see or anticipate when a bike is about to cross a street, alley, or driveway. Meanwhile, cyclists are relatively unaware of their surroundings compared to pedestrians, for the same reason that motorists are: They're moving faster. These two factors can easily combine to create a sudden use-of-space conflict that cyclists never win.
You're less visible on the sidewalk than in a lane, and you pose a threat to others. I'd almost go so far as to say, "Cycle where you're supposed to, or don't cycle." Moving in unexpected ways in unexpected places is what leads to collisions.
While your factual statements are true, and cyclists on sidewalks can certainly be a menace, I don't think it's really tenable to argue that cyclists should always be textbook road users unless you also ensure that everyone driving larger and motorised vehicles also plays by the rules.
I live in a city known for having many cyclists, and there are always tensions between the local cycling population and the authorities about the poor level of law enforcement against dangerous drivers. Of course, there is also a poor level of law enforcement against cyclists doing dumb and illegal things. The difference is that when something goes wrong, it's usually the cyclist who ends up injured or dead, not the motorist.
So while in an ideal world we'd all get along nicely and play by the rules, I don't tend to get angry at cyclists whose choices are illegal but obviously safer (as in, I've read the actual research and current law and/or public policy clearly doesn't promote the safest option, not just doing something that intuitively feels safer but maybe isn't really).
"The difference is that when something goes wrong, it's usually the cyclist who ends up injured or dead, not the motorist."
In the case of riding on sidewalks where it is inappropriate, it's also frequently a pedestrian.
"I don't tend to get angry at cyclists whose choices are illegal but obviously safer (as in, I've read the actual research and current law and/or public policy clearly doesn't promote the safest option, not just doing something that intuitively feels safer but maybe isn't really)."
In those cases, I agree that the cyclist should do what's safest (presuming it's safe enough - on balance - for everyone involved). So should drivers of vehicles, for that matter. My understanding is that taking the lane, where traffic is moving at a speed the cyclist can keep up with, is the best way of keeping everyone safe (I wouldn't be recommending it otherwise). You are right where everyone who might hit you can best see you. I say this as someone who cycles in a big city fairly regularly, with a spouse who bikes in a big city even more regularly, in the wake of biking safety classes. I'm not just an annoyed driver/pedestrian/whatever trying to keep the cyclist down.
Your point illustrates the subject line nicely. Very many people have a disability, yet you're suggesting very rare benefits of keeping kerbs that hamper people with disabilities.