In sparse areas, going to the same few options over and over again isn't fun, and they tend to be more expensive, maybe due to lack of competition.
A functional rail network allow the public to move with much less restraint. Think about it. A highly car dependent society which much of the world unfortunately still is, will make going to 3rd places much less attractive. Easier to sit at home, doom scroll and watch Netflix.
Inter city trains should run at least every half hour, reliably.
You can just go where you like, and if you want to go somewhere else, sure it might not be the strictly fastest option, but it sure is convenient. You can go from A to B to C to D to A without having to go back to B to grab your elephant box and bring it to D.