This is the same reason that the radio blares idiotic garbage while real music lives in dive bars and underground venues. The masses need uninspired nonsense to fill their minds and allow them to live without thought.
This truth transcends all mediums (Hunger Games, Nickelback, Twilight, FoxNews).
If you want to become commercially successful creating something, know with a grim certainty that you will have to compromise your art. If you want to stay true to your passion, know that your chances of commercial success are slim to none.