My own theory is that the "special editions" were intended to change as many frames of the movies as possible, even the parts that weren't broke, in order to seize revenues/royalties from whoever (presumable 20th Century Fox) was getting paid the lion's share from each showing/sale of the original editions.
"This isn't your father's Star Wars" means that Lucas deliberately ruined his own legacy as an artist in order to grab even more cash. And Disney which has no artistic legacy at all when it comes to Star Wars is even less likely to give away its precious revenues by restoring and marketing the original versions.
Imagine if Rembrandt's art studio received major backing from a corporation in return for a profit split ... but he found that he only needed to buy some tubes of glitzy neon paint at the craft store and scribble all over the old paintings, slap a new copyright on them and "tah-dah".
On the other hand, it is well known that Lucas regarded Hollywood films not as Rembrandt paintings, but as "American Graffiti" which in that case means, what the hey, go ahead and spraypaint meaningless tags all over your previous graffiti.
It doesn't square with him trying to endow a "Star Wars Museum of Narrative Art" ... but at least he has an out.
