Cheap Flights from San Jose to New York from $168

Everything was great, but when I booked 5 planes w jetblue, our last flight was a 6 hour lay over. I saw another one with an hour layover, (still jetblue) while at the terminal. They say $150 to change the seats to the earlier plane. Seemed like not good customer service. Why not? It doesnt cost them a penny more.