What Superman needed was a change in visual aesthetics in terms of art and a more focused continuity in terms of more firmly nailing down the canon. For instance just changing from Swan to Byrne or someone of his pedigree alone would have given everything a fresh new sheen. Also a tweaked history that firmly got rid of some of the silly stuff they wanted to distance from (Superpets and Superdickery) without completely canabalizing everything.
Ironically, a lot of what Byrne touted at the time as being essential to "fixing" Superman was already more or less happening. Supergirl was dead and Kandor was shunted to another dimension. Krypto barely appeared anymore. Effectively Superman was again alone in terms of being the last of his kind. Kryptonite was no longer as ubiquitous as it once was.A more balanced Superman/Clark dynamic was already in place. Luthor shifting away from criminal mastermind to businessman was something even Maggin was toying with around that time. An organic shift,an evolution was already occurring,but far more organically (much like Batman in the later 80s).
The biggest issue is they threw out the baby with the bathwater. Byrne and the higher ups at DC didn't need to. Just a change in the look and a shift in story focus to less high concept stories and more to a fleshing out of the existing world around Superman would have worked the same way WITHOUT tossing away all the old toys if later creators wanted to use them. Yeah,some of the Post Crisis additions were cool,but I really can't think of anything introduced then that couldn't have coexisted with all that came before.
Superman only needed a streamlining and a few minor tweaks to his history. Not see the complete dynamics of the character and his world turned on their head for short term gains. By the later 90s I think DC realized they went a little too far in stripping away large swaths of the mythos and attempted,clumsily,to reinsert those things,which ultimately led to a Superman we had in 2011 with a history so convoluted no one knew anymore what was canon or not. Hell,they haven't still for 6 years.