I can only guess, but maybe Sony is waiting for Ep3 to put out a huge prequel trilogy box, ala LOTR will eventually have. I know that the OTC 2-CD sets are on another label(BMG?) and are still in print. Wouldn't suprise me at all to see new 2-CD soundtracks with the new DVDs. Anyway....
I enjoy John Williams work a lot, for example, Catch me if you can was a very cool and clever soundtrack.
I like the 2-CD Ep1 soudtrack a lot and just feel a little cheated that the same for Ep2 never got released.