I've witnessed directors with a vision I may not have predicted, but which turned out to be obvious later for better or worse.

One way I side with the poster is in consideration of posting an age range for auditions IF the age range exists. Peter Pan is an oddball case though, where the director may have secretly hoped for a Mary Martin type in the role but had to see all comers just in case. The key word is consideration -- I have seen directors waste the time of talented people because they simply didn't have their vision planned out and were hoping things fell into place for them instead. That's just inexcusable!

I hate the traditional casting of a mature woman as Peter Pan anyway (just plain creepy) and I hate that particular Broadway musical, so it's hard for me to cast judgment on just how wrong the casting can go. =)