Yet, this is the general view in a given SW forum:

I have been led to believe, that Lucas won't release the original theatrical versions, because if he does, he will be forced to pay his ex wife Marcia royalties, as she was involved in the editing process, on all three OT films.

She took half of his wealth when they divorced in 1983 (but left Amanda behind? What a great Mom!) Marcia crippled Lucasfilm and left Lucas broke. He had to build his Empire back up. If that hadn't occurred, we would have gotten the first Star Wars prequel in 1989 (which was the original plan) and we may have even gotten a third trilogy (my speculation here) starting in 1999.

This is partly why he changed the OT movies for their 20th anniversary; change them just enough and they aren't totally the same movie any more and he wouldn't be under any legal obligation, to feed her any more dollars. He got away with releasing the original cuts on DVD, as they are 'bonus features' If my missus left me and our daughter, for an artist who worked for me and took half of my Empire; I wouldn't [censored] on her, if she were on fire, let alone pay her royalties for a film series, that isn't even hers to begin with.