I have a lot of DVD's from the early release days and most of them were laserdisc masters re-used.
It's pretty much a hit or miss prospect. Sometimes it's pretty nice, sometimes it is foul and unwatchable.
Ever see John Wayne's the Quiet Man? The Anniversary laserdisc looked nice (for laserdisc), the DVD transfer from the same master is unwatchable because of grain that looks like a black snowstorm. Sometimes modern transfers from these laserdisc sources aren't a good thing.
In 90% of these cases the films are later re-released struck from a better quality source in anamorphic because it IS better and modern viewers find the older quality unacceptable. George Lucas has to expect that we would too.
Edit: Can someone clear something up for me? Are laserdisc masters a film source or some sort of analog magnetic tape? If it's still on film, can't they scan it at a higher resolution and digitally resize it to anamorphic like the rest of us do?