that's the best answer I could think of to your very valid question. 
I think it is a very fine answer indeed. My opinion even goes a little further.
'The Great Musical Disaster', as I would like to call it, found place around the second half of the 18th century, when the audience and performer became seperated. Concert halls being build for the purpose of concert giving. A place were people fool themselves by thinking it is in any way a culturally enriching event. It is not at all. People who go to concerts, and those who admit that they do, are doing a terribly fearsome admission about themselves I think.
When one enters a concert hall and goes to an event, (s)he enters a certain atmosphere of bloodlust in which the audience is just waiting and preying upon the performer to make a mistake.
This, of course, obviously causes that the performer will only limit himself to a not so broad horizon of repertoire. (S)he will only play the pieces (s)he really is familiar with and can play with the utmost confidence. And because in the concert hall, you simply have to project the piece to the guy up on the second balcony, so to speak, you will add all sorts of tricks and little nice ornaments, which will be ingrained into the pianist's hand memory.
In my opinion, we should involve the audience much more, in a time of technological revolution, in the experience of performing the music. Also, I think we should maybe slowly accept the fact that concert-giving was a nice experiment, although maybe not so nice in my opinion, for about two centuries, but we now should abandon it.
Just my opinion. I might start a topic on this one. Hope I won't get expelled from the forums!
BW,
Glenn
Topic: Bach Little Prelude: A Little Gem