For the 2004 dvds, did they not restore the original film elements first, and then made changes like the "color correction" and CGI additions?

I'm sure someone will have a real answer for you, but as I noted in my ANH thread, if you watch the transition into the Jabba scene on the 2004 DVD, you can actually see, briefly, elements of the 1997 SE Jabba.

Not that it would take a massive amount of work to restore the bits they didn't restore to the same level, and splice them in, but does anyone really think that will happen?