Seat, on our route to Berlin many of our passengers are Polish. On our routes to REus and Girona (Barcelona) not everyone wants to go to Barcelona: there are other places.
People choose FR for 2 reasons: price and convenience.
For example, I much prefer Bergamo to Milan, hence I would always fly to ORI rather than MXP or LIN. If I want to go to Milan I can always get the train. Equally ORI is convenient, as is Brescia for Venice as I can get the train to the main station, which takes 2 hours from Bergamo, 1 and half from Brescia, as opposed to an hour on the water bus from Marco Polo.
Hahn suits me for the Mosel valley if I fancy going wine tasting as Bernkastel is just down the hill: Beauvais on the other hand is a waste of time for Paris and Charleroi I don't rate for Brussels but I'm a big fan of the Eurostar for both destinations.
You can't generalise: we all pay our money based on or needs and perceptions. What suits you doesn't suit Fred next door and vice versa.