DC's done a pretty good job of that on their own haven't they?
Precisely. I'm thoroughly convinced that DC did not think this reboot through as much as they should have (see my Joe Q. comment earlier). They wanted to increase readership, thus sales, and particularly among young readers. Understandable. Unfortunately, they decided not to focus on little things like "details" as to how some of the stuff they insist "still counted" could've happened if everything else is wiped away. It would have been better to take a page from Marvel's guidebook and create a separate universe line.
I've been saying for some time that, as much as I want more stories with Cassie and Steph (the latter grew on me as Batgirl), I don't want them brought back in the New52. DC is determined to annihilate them, not for creativity, not for dynamic storytelling...but because some editor just "doesn't like them, doesn't get them." Kind of like how some TV executives who "don't like or understand" action shows are put in charge of a network or studio's action-based programming (I hear that's why X-Men: Evolution's first season was so ho-hum).
Call it mild egotism, but it's sort of a "if you want it done right, you've got to do it yourself" feeling for me.