I am torn. I agree that Cass deserves a better parent than Bruce. But the adoption made her an official member of the Bats family. And, yes, they could choose to ignore it but it would still be in continuity. With the retcon there is no connection making it easier for Cass to be even more marginalized, if that's possible.
If anyone's going to be adopting her, it should be the parental figure who actually gave a shit and treated her with some basic human decency.
I would have loved to have seen Babs adopt her. Although her recent treatment of Misfit gives me concern about her parenting skills.