With all due respect, Ady, and apologies for what might have come across more negatively than it was intended, but I don't think you can compare where we are now to where Lucas was in 1975. I work in the industry and my ex works for Framestore, so I know as well as anyone what can or can't be done, as do many of us. I'm talking about us here on the forums, with our limited resources, make alterations to these movies. And some things can't be done with what we have now, meaning some of the mock-ups we've been doing.
And as for Lucas not having anyone to do his special effects, and him purpose-building ILM, yes, we know that story. But you make it sound like they invented visual effects, which they didn't. There wasn't a single technique used on the FX in Star Wars that was new; ILM didn't invent a single thing. I'm sure some people will gasp at me for that, but it's a fact. Not matte paintings, travelling mattes, motion control photography, animation elements (eg sabres and lasers) in live action - not one invention. The early ILM fellas, love their work as I have all my life, didn't do anything more than collate all the techniques that had been used before into one dedicated house. Yes, they revolutionised FX, but they weren't masters of invention in that period. Dykstraflex may have been developed more for Star Wars, but motion control was around for a decade before that.
Maybe I oversimplified when I said some things can't be done. I was more meaning they probably can't be done sufficiently well, given the time and money we have to devote to them. New sequences are all well and good, but match-moving is painfully difficult when you're dealing with shots that weren't intended to be FXed afterwards.