You always should weigh the benefit of the experience versus the hard cost in cash.
That is my point exactly vis-a-vis using public transportation. I think so many Americans, being unfamiliar with using a rail website, such as the Bahn's or OeBB's, think that rail travel is much more expensive than it is, so they opt for that with which they are familiar, car rental. But their perspective is usually not accurate. Public transportation in general, and rail travel specifically, in this area, can be a lot less expensive than first appears. You just have to know how to use the websites to get the best fares. For virtually every trip I've made in the past 15 years, I have made detailed plans and figured the price with public transportation vs car rental, both during the planning stage and after the trip. In every case, public transportation has proven to cost half or less vs the cost of renting a car, fuel, and tolls. I've never even figured in the added cost of parking because it was already obvious that public transportation was so much less expensive.
But, as you say, price is not the only consideration. One of the reasons I like to travel is to experience new things, things I can't do here, including eating different foods and using my second language. Public transportation in the US is so difficult to find and generally expensive (see Amtrac), so I find it a new and fun experience to use the trains in Germany and Austria. Using trains is one of the reasons I go there. With the train, I can use my time so much more effectively. Instead of staring at the road, I can watch the scenery, write in my journal, sort my pictures, figure my expenses, review what to do on arrival, etc.
I think the convenience of a car to get to small places is over-rated. I've spend over 150 nights in Germany, and over half of those places have had less the 10,000 population. And I got to all of them with public transportation. As the Youtube video pointed out, it would be just as easy to get to the ice caves and Five Fingers by bus as by car. When I went to Hallstatt a few years ago, I was able to stop on the way in Mondsee.