Probably because her original series sold like toe fungus and has been out of continuity for years now.
Not that it's bad per se (aside from the "child rape" nonsense, and the whole "the assassin is named Omerta" thing), it's just utterly unremarkable. None of what makes her compelling now is really present yet, and it's completely isolated from both the rest of the DCU and the character as she is now, so nobody cares about it, so nobody talks about it or references it.