Aside from the fact that George doesn't want to? Probably some score issues and such (for branching anyways) but I think that's pretty minor if the previous issue didn't apply.
Doesn't bother me, either way.
I know... I know. PPl will buy this version regardless.... and they will release the unaltered version eventually.
Of course they will, becuase George knows he can make more money this way. If he released the Classic Trilogy before the Special Editions, everyone would buy the Classics, and sales for the Special Editions would be poor. This way, he knows sales of both will be strong.