One of the ways that a film can be good is by being realistic. This often comes at a cost of being depressing or deathly boring, but realism is a plus. The trouble is half the time we have no idea what is realistic. What is American gang/drug life like? Being part of a professional sports team? I donno. But throw infidelity, alcohol problems or squalor (for drug movies) and it becomes realistic. They go for all this with serious bio-pics but usually change the details of the guy's life significantly. James Grey's book "A million Little Pieces" was a smash hit because of its unflinching look at drug life but no fact in it could be trusted. Sean Penn's new movie "Into the Wild" is getting rave reviews but fabricates a traumatic childhood to explain the guy's weirdness.
Realistic films do lots of things, they stimulate our imagination, inspire empathy present other sides of the story etc. Rooting out oversimplifications and implausibility is all cool. But it quickly becomes simple dishonesty if we tolerate fabrications because it helps make a point we like. And that is very bad.