Simply, total continuity is impossible, sometimes it can be repaired, often with disastrous results and it still isn't repaired, i.e, crisis, zero hour...
Changes like this are interesting, and what we all like to talk about and debate, but I can wish it to never change but it has to, eras change...
You are absolutely right, Matter-Eater Lad. Total continuity is impossible, simply because people make mistakes. That doesn't mean, however, that the attempt to make things fit together and make sense with the past is destined to failure forever. The trick to building good continuity is to look at all the pieces, fit them together, find patterns, and build on that. Even mistakes can be a strength when building continuity; look at the wonderful job Busiek did with AVENGERS FOREVER, reconciling mistakes and flaws, so that not only are they NOT mistakes and flaws, they're explanations that can be built on to create a story.
And sure, times change, but let's face it: the Silver Age was, well, BETTER than other periods - not because of nostalgia or sentimental reasons - but for the very concrete, real, and simple reason that there was a giant glut of talented people.
In any given year of the 1960s, we had Stan Lee writing just about any Marvel title of consequence; Jim Shooter and Curt Swan on LEGION, Mort Weisenger watching over the Superman titles, with John Broome, Gardner Fox, and Edmund Hamilton on most other DC titles. In any given year in the 1970s, we had Steve Englehart writing AVENGERS and DOCTOR STRANGE; we had Jim Aparo doing BRAVE AND THE BOLD; we had Elliot S. Maggin writing SUPERMAN and Cary Bates doing LEGION OF SUPER-HEROES, there was Steve Gerber writing DEFENDERS; there was Jack Kirby doing his Fourth World comics and KAMANDI; even the worst stuff of the Silver Age, the lowest stuff on the spinner rack, like Gerry Conway's run on FANTASTIC FOUR or Marv Wolfman's TOMB OF DRACULA, stand much higher than even the
average comic of today. I'm not quick to blame it on gimmicry like our moderator Super Monkey is; Comics are founded on good-natured hucksterism. One can blame the rising cost of comics, but that's not the answer either - it isn't that comics cost a lot, it's that very seldom do you ever feel like your money is well spent. Rather, I point the finger at "decompressed" storytelling, and just plain old failing upwards, with peopled assigned to comics who just can't write (yes, I
am looking at you, Chuck Austen, Keith Giffen, John Byrne, Brian Michael Bendis, Dan Jurgens, Mike Grell, and Warren Ellis).
The only people working in the Modern Age I would say are equivalent in writing ability to people like Bates, Maggin, Englehart, and Gerber would be Alan Moore, Kurt Busiek, Dan Slott, and Christopher Priest.
I don't mean to slight the Golden Age either, but the fact is, while there were very many talented people that worked in those times, it simply wasn't as good as the Silver Age was; there were talented people, but not AS many talented people. To be totally fair, there were bright spots: Moulton Marston's acid-trip brilliant though creepily sexually deviant WONDER WOMAN, Kirby's CAPTAIN AMERICA, C.C. Beck's cute MARVEL FAMILY. and Eisner's SPIRIT. For the most part, Golden Age plots were centered on rote; all ending with a knockout punch to the bad guy's (glass) jaw that clocks him. Further, while the Silver Age was centered on innovation, the Golden Age had heroes that came in basically two flavors: Superman clones and Batman clones. For the Love of God, count the Batman clones of the Golden Age: the Black Terror, Catman and Kitten, the Grim Reaper, even Green Arrow, whose archery gimmick cannot not hide the fact he was based on Batman's blueprint. To be fair, their is plenty of ugly plagiarism and derivativeness in many Silver Age characters and concepts, but the point is, it was not institutionalized to the extent it was in the so-called Golden Age. It should even be noted that even people that worked during the Golden Age, like Jack Kirby and Gardner Fox, do their best work in the Silver Age.
Just about every imaginative concept that exists today in the DC Universe was created in the Silver Age. The Flash, for example, was exclusively a product of the Silver Age; Gorilla City, the Cosmic Treadmill, even the dimensional travel that let the Golden Age continue in some form in "Flash of Two Worlds" was a Silver Age innovation. Superman's uniqueness is almost entirely the product of his Silver Age stable of (genius) writers and his (genius) god-editor, Weisenger, and while the E.E. Smith Lensman-concept (let's be generous and say it was "borrowed") was hardly original, applying it to superheroes WAS; thus we get Green Lantern and more innovatively, the Green Lantern Corps.
Roy Thomas, that sentimental genius, got a lot of mileage out of Earth-2, but the fact is, the Ultra-Humanite is no Luthor. The few villians that the Golden Age produced required research to unearth. Even then, it should be noted Thomas drew out so many concepts not from DC's history, but from novels like GLADIATOR and movies like METROPOLIS and KING KONG. And no matter how you slice it, the villian-impoverished Earth-2 has no Darkseid, no Weather Wizard, no Star Sapphire, no Brainiac, no Sinestro, and an Injustice Gang made of the same faces over and over: the Wizard, the Huntress, Sportsmaster, and that violinist with his magical violin.