In the end, most people go to a movie theater for escapism. So, Hollywood is always going to lean towards appealing to the masses.

So, that's why for the majority of film history, movies have been beautiful people, in beautiful settings saying perfectly-crafted dialog.

The 70's was a real break from this. Some of my favorite movies are from this era because of this. Early Spielberg was really great at doing it. He would ground his movies in realism upfront. People were sweaty, houses were unkempt, hair was a little messy. That way, when the fantastical part of the story kicks in (Jaws, Close Encounters, ET) you are bought in and along for the ride. But even he got away from it and his later fantasy films (Hook, War of the Worlds, A.I.) have that glossy sheen on them all the way through.