For an event that was intended to clear up a confusing* continuity, it sure feels like DC Editorial went out of their way to re-confuse it from the get-go. About the best take on its legacy was in (of all places) Grant Morrison's Animal Man, which picked up the thread of the Psycho-Pirate's lone recall of prior continuity and how it dovetailed with Buddy's old existence, all pretty elegantly. Though Morrison later became the second-greatest perpetrator of exhausting continuity-porn with X-number of follow-up Crises, a good example of an author not knowing when to move the hell on.

*Confusing is, of course, an entirely subjective condition and is really on the reader to sort out their response.

It wouldn't have been that hard, when the CRISIS ended, for the Legion to look back through time, discover this "new" history, and realize there'd never been a Superboy in it -- that could've launched a bunch of stories for them. 

Opportunity missed.

Rebooting WW also ruined JUSTICE LEAGUE OF AMERICA's continuity, which contained a lot of important stories.

Removing Superboy and Wonder Woman from stories that were STILL SAID TO HAVE HAPPENED reminds me of how the Soviets would totally scrub certain people who had fallen out of favor from books, statues, and even photos.  Just because you SAY something didn't happen doesn't mean that it didn't happen!

1. If it was mandatory Clark became Superman only in adulthood in Metropolis, Superboy still could have been part of the Legion (or its history at least) by simply establishing he only wore his costume in the future.  (His non-Legion adventures were never referenced anyhow, except for blowing off young Lex Luthor's hair!)  After all, Clark was still around and STILL had his powers and must have been doing SOMETHING during his teen years!  It's hard to believe that he would done NOTHING with them before he was an adult.  (The MAN OF STEEL movie's most ridiculed moments notwithstanding.)  Moving that "itch" to the future Earth actually makes sense!

2. George Perez's reboot of WONDER WOMAN could have easily been set in the past without hurting anything, as it was mostly self-contained.  The Earth-One/post-Golden Age Wonder Woman's history had never really been fleshed out anyhow.

3. Or just start a new Earth 3!  A clean start for everybody.  Earth-2 was increasingly far removed from all the WWII era origins for everybody  and all the favorite characters were doomed to die of old age and be supplanted by legacy replacements anyhow (which is what happened!).  The piecemeal explanations for Black Canary being young, Hawkman's still super-convoluted origins, and the other "fixes" still grate decades later.

As a young adult who still enjoyed the stories I grew up on, I was initially very excited by CRISIS and to see the end of some stories and the potential of new stories going forward.  After two years of uneven and unsatisfying patches and a continuity certainly more confusing than the simple disclaimer "This story takes place on a parallel Earth where some of your favorite heroes are older," I ended up quitting DC for over a decade, even though I still loved the characters and will forever love the comic book medium.  At least with Marvel, I could return whenever I wanted and revisit my other favorite characters and not worry about wading through decades of piled up story band-aids.