For all the confusing plotlines that the Crisis cleared up, it also wiped out a hell of a lot of good things, and this is one of them. Earth-2 was really one of the more logical takes on superheroes out there, if you think of it, because it took DC's classic heroes and allowed them to grow old, allowed them to die, allowed them to retire and have kids, just like they were real people - while keeping them intact in the regular universe. It worked very well, in my opinion, and gave us so much good stuff - Power Girl, the Huntress, Infinity Inc., Jade and Obsidian, etc. It's an awful shame that it got wiped out.