Well, if I'm a company using rail for freight or a worker depending on the rail to get to work, it already is a massive improvement if I can at least rely on the train being where it should be at the announced time. Improving the schedule for faster travel or shorter intervals is another thing, but predictability alone makes my life easier.
In the Swiss case on time is critical because they want people to depend on their next train being there when they get there. They assume most people will get off one train and get on another (or a bus) so they all meet in the same place at the same time. Early does nothing for anyone unless the bus/train they are meeting is early and leaves early. This is one good way to run a system. The other is run so many trains/buses that whenever you arrive there is another waiting for you that will leave as soon as you can get on. This second way to run a system is much faster and better for everyone - but the costs are significantly higher though and so nobody can afford to run a large system that way. (large cities often can run this way and should where they can). Note that system is the key word here. If you only have one train the considerations are different.
Thankfully I don't have to take the train very often - especially these days lol
Perhaps also because it's still working.
A few people in one town having to wait an extra 20 minutes ensures hundreds of thousands have a predictably on-time system.
In general though, I'm so used to the trains being on time, I start tutting if it's even a minute late
Meanwhile, I've arrived in NYC fourteen hours late on Amtrak.
On the polish site which tracks punctuality of trains, you can often see train delayed for some time, which decreases delay by every stop, eventually ending with smaller delay or on time.