I enjoyed Steph as Batgirl, but that was when Barbara was still in a wheelchair and there wasn't any recovery on the horizon. Barbara was also older then in the
pre-New52 days (though probably not quite as old when she was originally introduced back in 1967, when she was a college graduate (likely with a masters degree) working for the Gotham City Library and Dick hadn't even graduated from high school yet).
But they severely de-aged Barbara for the
New52 and seemingly reduced the amount of time when she wasn't Batgirl. It would be much easier to just come up with a new identity for Steph (if people aren't happy with her Spoiler name) than it would be to drop Barbara as Batgirl (and all the $'s they make from marketing Barbara that way!) just so Steph can use the name again.
(And also, how many people who weren't around when Steph was Batgirl will buy into the change from Barbara as Batgirl?)
It's really pointless to expect DC to change that situation at present, and even if they did, how likely would they be to come up with a Steph-as-Batgirl series as enjoyable as the one we already had from 2009-2011?