It seems to obvious to me that Brown/Cain are shelved because DC wants to emphasize Barbara Gordon first and Batwoman second; it's about dilution. But the twist is that they not only want to emphasize the current Batgirl and Batwoman (and the current Flash), they have an even more vested interest in "proving" the claim that people were clamoring to get Gordon back (and Barry Allen, etc). The DC architects wanted this, but they want you to think you wanted it, too. We were always at war with Oceana.
Sarcasm aside, it makes sense to do it this way. It's their IP farm, anyways.