Your last four points are good, but in practice the first two have not netted significant advantages for NYC's bus operations: many of NYC's buses run on narrow one-lane streets, where any amount of double parking makes the road completely un-navigable. Similarly, it's more common to see a bus route taken out of operation entirely for a week than to have it re-routed on the fly (the latter does happen, but the network also dense enough where most riders can take the next avenue's route).

I think a significant understated advantage to streetcars is their effect on local neighborhood development: like a subway line, a streetcar line is a semi-permanent installation that can't be easily taken away by a short-term replanning of the network. Bus lines, even when dense and well-developed (like NYC's are!), simply feel impermanent in a way that rail transport doesn't.

(Or as another framing: if you build a rail connection to a neighborhood, there's a good chance there will still be a thriving neighborhood there in a century. It's not as easy to guarantee that with a bus route that can be taken away overnight.)

Rail-based transit also provides major side-benefits to its routes: development and improvement.

The principle is that bus routes can change, bus stops can move. Rail right-of-way and train stations are quite permanent and immobile.

Therefore, if a city invests in rail, the developers will follow, and redevelop, revitalize, or gentrify neighborhoods along that route. Conversely, folks in the neighborhood may fight the rail expansion, because "there goes the neighborhood" usually in a more upscale fashion.

It was smart for cities to build out streetcar lines in their early expansions, enticing developers into areas that promised long-term access. Of course, rail lines don't last forever, but the point is being more permanent and staying put, more reliably, than rubber-tire-based transit.