Beyond my own selfish reasons for wanting them I think Lucas does himself a disservice by diminishing the extraordinary things he and his crew were able to accomplish 30 years ago.
Agreed. Not only should their original work stand forever as a testament to the incredible leap they were able to make in filmmaking, but the original FX are what give those movies a HUGE part of their charm.
To me changing the OT is like going back and redoing all the FX for the original King Kong or Jason and the Argonauts. You'd be destroying what made those movies so unique and memorable in the first place.