People these days are generally lazy, its easier for most people to get to a train station, hop on a train, possibly change onto another one and go to their destination, rather than get to an airport, check in, wait for ages, then get on-board, fly, then deboard, leave the airport, and find a way from your arrival airport to your destination, where as most railway station go within 30 minutes walk of town centres.
Not sure if people are lazy. Maybe they are simply smart - based on your description of the differences between the two modes of transportation.