Lucas is adding even more changes to the special editions. I vaguely remember seeing something that he may make Han shoot first in the bar again, so at least that would be nice.
A couple of people have said things along these lines, where's that information coming from?
Personally, I too am not a particularly big fan of the special editions. Not only because of the infamous 'Greedo' incident, but because most added scenes don't do anything more than make the films more 'Political Correct' and add cute, funny robots and/or animals.
(This should has served as a warning for what to expect in episode 1, but for some reason no-one saw it coming. Perhaps if people protested then against these comic-relief additions, we might not have ended up with Jar-Jar Binks)
However, having said all that: I would still LOVE a new 'definitive' version of Star Wars, but not for the reasons others have already uttered.
Reason #1: Lucas has made his prequels in such a way that a linear viewing of Star Wars (starting with episode 1 and ending with episode 6) is encouraged. Just think of the entire 'Senator Palpatine and Lord Sidious are not the same guy' routine. For future generations, a linear viewing might even be more rewarding, but only if the original films are more enhanced special effects-wise. Otherwise, episode 4 would seem very underwhelming right after watching the no doubt mind-blowing spectacular finale of episode 3.
Reason #2: I would love to see Darth Vader and Obi-Wan really ripping into eachother in episode 4. Because c'mon, that fight looks silly even compared with ep5 & ep6, and especially when compared to the prequels. If CGI can create a spectacular fight between a senior citizen (Christopher Lee) and a cgi-character (Yoda), CGI can also add additional fight scenes between the late Alec Guiness and someone who is fully covered by a suit.
Reason #3: When you look at it now, the added CGI stuff from the special edition looks MORE outdated than the original footage. The original Star Wars kinda has this 'timeless' feel, even with the limited recourses Lucas had when filming it. In the definitive version, the added CGI could be enhanced and be brought up to par with episode 3.