The OP didn't say one word about precasting.  That's another topic.

Consider that Theatrebrat, no matter how talented she is, may have been simply wrong for the role, at least as the director envisions it.

Ty, haven't you ever heard one of the most famous phrases in the theatre?  Namely:

"That was the best audition we'll ever see for that role.  Too bad we can't use her."

Are you suggesting that the people who audition should be cast, regardless of their talent, availability, suitability for the role, and so on?

For example:

Our local theatre is doing A Few Good Men right now.  Let's say that I had auditioned for Kaffee.  Some other guy gets cast.  Now, for reasons beyond everyone's control, they have to move him over to play Sam.  Should I automatically be cast as Kaffee?  Would it change your mind if I mentioned that I'm about 20 years too old and at least 75 pounds too heavy to even be considered for the role?  Should the director cast me, just because I auditioned (and I guarantee, I would give a great audition for the role!), or should he look outside the auditions for somebody who could actually be accepted by the audience in the role?

What if I audition for the lead in Fences?  I'm a bit too white to pull that one off.

I understand the concern that the community (of actors) be served by the company.  However, I think the director's responsibility, primarily, is to present the play as best he can.  The director in the OP must have felt s/he couldn't do that with Theatrebrat in Role A.  Now, s/he might be right, or might be wrong.  But I don't think it's inherently wrong to cast someone who didn't audition in preference to someone who did.

Yes, someone who auditions gets points for wanting to do the show.

No, that shouldn't be the only factor.

There are far too many people out there that behave in community theatre as though it were professional theatre. (I would imagine most who are guilty of this are those who are bitter that they never made it professional.)

Wow.... Great post.. Wish you guys hadn't used up all the really good stuff already.. But seriously, like gaffa said, you always precast in your head.  You would be a fool not to. IMHO a board or play reading committee would be crazy not to do a little of that brand of mental math before selecting a show. i.e. "Do we have "THAT" kind of actor avaiable.  Heck, I can't even read a book or play for pleasure without casting it in my head.. But I think the important thing, as many have already mentioned, is to keep an open mind for the talent that walks through the door. Yet again POB14's quote (which I have never heard but will definitely be using in the future) puts in all in perspective.

We have no idea what "math" was being used to make these decisions. And there are always so many variables.  i.e. "Does that group really look like a family.." "Gee that part demands a thin person (fat can be faked)" "Ohhh my god, look at the conflict sheet".. Or in fact, the person may not even have auditioned well. Or may have a history in reliability problems..

Now in no way am I implying any or all of these to be the case in the opening of this post.. But there is no way for us to fathom the director?s mind in a particular case..  And yes, I get way ticked when I think I was better for a part or get bumped by a ringer... But that too is part of the game..

Bottom line that one hopes for in all productions is that the director is ultimately doing what he/she thinks is in the best interest of a quality show.