AP: Why did you change your mind and decide to put the original three movies out on DVD now?
Lucas: Just because the market has shifted so dramatically. A lot of people are getting very worried about piracy. That has really eaten dramatically into the sales. It really just came down to, there may not be a market when I wanted to bring it out, which was like, three years from now. So rather than just sit by and watch the whole thing fall apart, better to bring it out early and get it over with.
From an interview with Lucas.