I don’t know that I can whole-heartedly agree with each of this author’s opinions, but he makes some very solid points, particularly when he says:
And I don’t think it honors the art form [art music] for us to maintain such a cadaverous body of rules.
Being one who appreciates decorum, I find there are times when clapping is absolutely inappropriate. But with a sensitive audience, the music should communicate what response is appropriate and what is not. (HT: John Gardner)