On most trains in continental Europe, the price of a first class ticket is 1.5 times the price of a second class ticket. Even with that small price diffence, only few people chose first class (maybe 10-20%). But also there is no added flexibility, as both first and second class tickets are refundable and exchangeable. However more and more tickets are now sold as "special deals" and certain restrictions apply. I remember having seen a survey done in first class train compatments about why people chose first class. The typical answers were: "less noise" and "travelling with similar people" i.e. other businesspeople opposed to families.