I consider the level of pollution to be minimal. It’s not even noticeable in many US cities. Plus this is also always improving, particularly with increasing popularity of hybrids and electric cars.
> extremely dangerous to other road user
First off, “extremely dangerous” is hyperbole. The number of fatalities on roads is very low, and it will keep getting lower as safety features like blind spot monitoring become standards. Roads are already incredibly safe - in the US the fatality rate is something like 1 per 100 million vehicle miles.
But safety is also why roads should be reserved for motorized vehicles. Your assertion also seems very one sided. Safety is a two way thing - a substantial portion of bikers put themselves in danger by riding where they really shouldn’t.
> take a lot of space on the road
They also provide a lot of utility, which is why taxpayers funded roads and parking spaces to begin with. I, and I suspect most people, don’t mind using space for things that are high value, like cars.
