Pre-casting roles in Amateur theatre.

I had raised the question of pre-casting in regards to an audition notice that appeared for Playlovers end of year production of "The Talented Mr Ripley" with mixed responses. I am of the opinion that as community theatre, there should be a responsibility to the community that everyone should have an equal right to audition for a role. Ultimately the director makes the decision in regards to casting, but to not even allow people to audition for a role because its already cast, seems close-minded and short-sighted to me. Granted I probably shouldn't have initially made my opinions as a reply to that post, so I have decided to submit this blog. I want to know how other performers feel and directors feel about this and do you think its fair? Another can-of-worms that I want to open is the notion of Pre-casting roles with a Director, MD or Choreographer. To me this moves from unfair to Ludicrous! How can you concentrate on your role of Director/MD/Choreographer when you are thinking about your performance? I know there are times when someone falls sick and these people need to step into these roles. Thats different. What do you think?