[kgermino]

The thing is "They're also smoother and so more pleasant to ride. " is the only thing on that list that's even remotely inherent to trains over buses. Yet you rarely see people arguing to improve the buses so the other things you mentioned aren't an issue.

[cameldrv]

Ok, but if you take a bus and do all of the things I mentioned to it, you end up with a "rubber tire metro", which does exist, and is used in Paris and Mexico city, at least. These are basically indistinguishable from a passenger perspective to a train. The smoothness of trains is really out of necessity. If the tracks weren't smooth, the train would derail.

[tacticus]

Capacity is significantly higher and stop frequency significantly lower allowing a high speed high volume route.