> the idea of all wagon individually powered is ancient, very ancient, like monorails. Both ideas never get spread simply because they are too expensive instead of cheap, in practice. > it sound extra added complexity for little to no return

What on earth are you going on about?

The vast majority of all current and new passenger trains in the EU are multiple units with no power car, because they are pretty much better in every possible way. They are cheaper to build and cheaper to operate(mainly due to being lighter overall) and can be shorter without reducing passenger capacity. Only a couple of the wagons are powered, more is not needed.

> hyper-fast accelerations are not much welcomed by passengers

Passengers want to get where they are going quickly. No train accelerates at a speed which causes discomfort to passengers.