The problem is
that the edited version of the Orff has become so recognised, that if one were to play the proper version, people would get bored. Ditto with the 'Dies Irae' from Verdi's Requiem, anything from the Mozart Requiem, and Borodin's Polotsvian Dances. People are used to hearing extracts of thrilling, explosive choral music, without realising that there is often a lot more to the piece of music that is actually even better (but not as impressive) than the "famous" bit.
(The Empress it seems you CAN polish a turd!, Tue 2 Dec 2008, 10:10, Reply)