The '97 Special Edition was often marketed "The way Lucas originally envisioned it". The simple truth is that most of it was research & development done for the upcoming prequels all paid for by Fox. That's why most of the updates are so random and out of place. If the new additions hurt the story or pacing never was a question it seems. And with this R&D approach you simply don't get a nice finished product, you cannot add or update one effect to state of the art of '97 and leave other effects state of the art of '77 untouched. So even the more nice looking CGI effects like the added sequence of the Falcon taking off from Mos Eisley feels largely out of place, not only does it hurt the pacing, make some earlier and subsequent effect shots look weak, the way it is shot simply don't mesh with the filmmaking style of the original film. In short, a Frankenstein monster...
Besides using these old classics as a vehicle for his R&D, you also have Lucas modern sensibilities for filmmaking that just boggles the mind; Greedo missing Han at point blank range, censoring of Imperials getting hit by laser fire, Luke screaming like a bitch (audio lifted from ROTJ) in his act of self-sacrifice in Cloud City, showing the audience exactly how Vader ends up on the Executor even though we all assumed he didn't use teleportation or flew from Cloud City like Superman, and on and on... often over-explaining to make sure we all see and hear what's going on, the wampa sequence is another. Except for the censoring, this is simply bad filmmaking, nothing left to your imagination, no subtlety allowed.
I guess I was referring to stuff like, the 2011 blu ray change of hiding r2d2 behind a rock during the Tuscan raiders scene. Why after 35 years would he change that? Changing obi wan's krayt dragon call? Items like those. They aren't enhancing the film, just changing it.
Basically the same reasons he did those changes in '97. New over-explanations, sprinkled with R&D for the upcoming 3D release I presume. He simply doesn't look at it from a story point of view or an artistic one when doing these things. If he did, the most logical would be to remove the stones hiding the fact that the landspeeder isn't hovering without support instead of adding rocks for R2-D2's hiding place, not even that stupid addition is consistently done or even makes any sense. For Obi-Wan's "krayt dragon call" in the original film, they used the same sound that was used for the dewback earlier in the film, with his track record of over-explaining things, I thought he altered it because the sound effect was similar to the sounds of the tusken raiders but it has now been changed twice. Now I am over-explaining. ;)