In regards to that, I think it's very indicative of the blinding arrogance that Lucasfilm has that their stated reason for breaking them into trilogy boxsets is not because *gasp* someone might only be a fan of one trilogy instead of the whole thing but because they might not want the bonus features.
But that said, I honestly believe that is at least part of the reason that the bonus features are kept off the single trilogy sets: to entice fans to buy the whole thing and soothe George's ego at the same time. Frink is right. It is a good business decision. Aside from a lot of us, Star Wars fans aren't very discerning customers to begin with. They'll buy anything. And for those that are a little more discerning, what better incentive to blow money on a prequel trilogy you don't care about than with the lure of deleted scenes you've been waiting almost 30 years for?