If we are talking about tone, then yes people sometimes get unnecessarily shrill. I wouldn't fret about the actors, producers and directors too much though; in my experience they are the most immoderate of all. Beyond that, however, if you are suggesting that people should not criticize, then I would suggest that you are suggesting disrespect because when we treat everything as good, and don't discuss what isn't, we are insulting the folks who do great work. Theatre is, to borrow a phrase, a hard-knock life for us.
On your other point, I agree.