The reason George Lucas doesn't want to release the Original Trilogy in its' original form is simple - money.
If he releases them as a set of remastered films (pre-CGI and Special Edition alterations) he has to pay his ex-wife Marcia a hefty payment, as she was an editor on the originals and it is written into this divorce paperwork that if the originals are released, SHE GETS PAID.
It's that simple.
The release of the original films as BONUS MATERIAL in this DVD set:
http://www.amazon.com/Star-Wars-Trilogy ... 326&sr=8-3
is the closest you will ever have to the originals on DVD.
A "bonus disc" for each film that contains the respective originals. And by originals, I mean the complete un-altered films the way audiences saw them back in 1977, 1980 and 1983. Even the added-in-'81 "A New Hope" in the title crawl of the first film is no longer there. It is simply STAR WARS. Simply put: these are the versions audiences (who were born before the 90s) fell in love with. These are the versions that made Star Wars a phenomenon.