If I could add just two hours to a trip and avoid having to go through an airport... almost any airport... that would be a no-brainer. The crowds, the lines, the waiting for no good reason... there is so much less stress involved in train travel!

And as noted by the OP, it's far more comfortable, plus you've got power available at your seat, so if you've been taking photos you can go through and edit them, maybe catch up on emails (assuming you have a simcard for your phone with cheap data), or just take a nap. If you're REALLY bored, you can download an app that gives your speed.

The only reason I'd fly would be if I were connecting from another flight.