I agree but disagree and agree to disagree.
I agree that the art changed with the artists on ALL-STAR COMICS, but that's to be expected with different artists and I don't agree that it was that different or varied that much in quality. Wally Wood mostly was an inker on the book, first on Ric Estrada's pencils and then on Keith Giffen's. Woody only did full art on two issues--64 and 65--and then he left. In his place were Joe Staton and Bob Layton from 66 to 72 and then Joe Giella took over from Bob for the last two issues of the run. Joe Staton did full art when the team went into ADVENTURE COMICS--with the exception of issue 465, where Dave Hunt did the inks.
Bob Layton was apprenticed to Wally Wood, so it made sense to choose Layton as Wood's replacement (and heck Layton may have assisted on some of Woody's previous inks). Joe Orlando was an editor on ALL-STAR for part of the run and I recall an interview with him from back in the day where he said he preferred to work with talent who were married and had a stable home life, because he could depend on them to meet deadlines. He might have been thinking of Woody when he said that--even though he and Wally Wood had a long association from back in the old E.C. days and Joe was one of the few people in the industry who still gave him work. Woody did not have a stable home life and he couldn't be depended on to meet deadlines, giving his editor grey hairs. This is probably why Wood was mainly used as an inker by National Periodicals, because that was less risky.
Joe Staton taking over from Ric Estrada makes some sense, too, since Staton had been inking Estrada's pencils on KARATE KID (one of my favourite short runs from this period). I think Estrada was a consistent penciller and Joe Staton was always a favourite from his days on E-MAN.
I like that ALL-STAR didn't grapple "with the fact that we're looking at superheroes many years on" so much. I think it did do that, but not to the extent that other runs may have done. Because how age and time worked on Earth-Two never was nailed down, so it's hard to say if characters had aged that much. This is something that, for whatever reasons, editors didn't take on--and maybe it's a good thing they didn't. I prefer super-heroes to be timeless. But Paul Levitz did like to stir the pot and bring in politics--showing that on Earth-Two there was no Apartheid, but also that Quebec had become independent from the rest of Canada (I doubt that Levitz fully understood the situation in Canada).
It wasn't just another super-team--it was the Justice Society of America and it was based on a completely different world from the rest of the super-teams at the time. That gave it its own atmosphere. And because it didn't have to work with the Earth-One continuity that gave Levitz a free hand. I recall an interview with him where he said he was attracted to the Justice Society and the Legion of Super-Heroes because those teams existed in their own continuity.