theatrics have their place.
theatrics should not try to make up for sub par performance.[/i] 
Just want to comment on this, I am not per se replying to you, but there is a fallacy in this statement by those who believe there is an 'intention' of theatrics to make up for a sub par performance. I do agree, there are those who do. and there are those who may do that sometimes.
But there are also those who do 'theatrics', not for the sake of theatrics, but it is just who they are. They are just being natural at the instrument they play at, whether they are good at the piece or not. For instance, I can speak for myself, I do a lot of theatrics, when I perform for my class, especially a non-introspective piece or a very dramatic piece (let say revolutionary etude) I am totally into it. And I make more motion and rocking of the body not only because it helps me to play it better perhaps but also emotionally I am and really feeling it. I am not inhibited in my expression of it. And for some reason it does relay to the class as something positive. as most in my class is shy and inhibited in really dynamically moving for their performance. They see it as maybe inspiration? i dont know, but it has been commented that it has been entertaining for them. My teacher also as well , enjoys my performances (no matter what level of progress I am at in the piece ) and appreciates I dont 'inhibit' myself from freely expressing myself with whole body and mind just because Idont play the piece well yet. I play it slowly as I am still learning it but still try to express through my play most importantly, but just like a golfer's swing or baseball player's bat swing follow through, i dont inhibit my phsyical expressions.
however, yes, there are those who play theatrics for the sake of it in itself. But just wanted to bring light to this. as all is not black and white.