What were Fox and Schwartz doing when they invented Earth 2? My understanding is it was a way to acknowledge the requests older fans had about the GA Flash. IIRC "Flash of Two Worlds" was intended to be a one-off. It proved popular so they did a sequel and then applied the concept to the JLA series. If they hadn't thought there would been good story in it or if it had flopped, they never would have done it or continued with it.
I'm a big fan of the Silver Age and
the post Crisis DCU. My JLA collection was built around the JLA/JSA team ups. COIE really put a crimp in those and other Earth 2 stories, but I never felt it was spit in the face. They shunted most of the JSA off canvas. The GA versions of Superman, Batman, Wonder Woman, Aquaman and Green Arrow were treated like they never existed. All-Star Squadron ( and later Young All-Stars) and Infinty Inc were canceled. ( even after being retooled). Still I didn't feel like a was spit in the face.
It was five years between Barry Allen's debut and Jay Garrick's return. It's only been a year since the New 52 started. I think they might want to take a little time for creating a "special place" were the previous continuity still exists.