Acting is very competitive. There are few good scripts out there and the ones that are good are very competitive. You look at your options and often times they're not too appealing.
I had acting teachers, and one of the things that was encouraged was to keep it fresh, to be spontaneous. That's the magic of film often.
I think a lot of directors, they come out of film school, they don't know anything about acting. Or they're writers that don't know anything about the process. And I think they're afraid sometimes to talk to actors and be honest with actors.