Stephanie Brown was not a true Robin. It doesn't matter if she were a male or female. The reason she obtained the mantel just negates her from being a true Robin, in my opinion.
She was a tool, literally. Batman only used her to try and get Tim to come back to being Robin. She is not memorialized because she was stripped of the rank of Robin, well before her death, because she couldn't follow orders. Not to mention she was only Robin for a handful of issues. Jason Todd was Robin for nearly a decade. She is not considered by Batman as one of the Robins.
She has been referenced as a loss in Tim's life more so than a loss in Batman's since her death. I would have loved a larger follow up to the fact that Leslie Tompkins let Stephanie die to prove a point to Batman, maybe that will happen one day and make Stephanie Brown a name again.
But no- she should not be immortalized in the Batcave. She was an independent hero, Spoiler, not a Robin. She was a cool character and great love interest for Tim Drake- but not a true Robin.
And seriously, if you didn't know that women are ALWAYS overly sexualized in the media compared to men, where have you been? And couldn't one argue that depicting the superhero's with 12 packs, huge pecks, giant biceps and bulging underwear is overly sexualizing male characters? Barbara Gordon was shot in the spine, and left to die while a male took pictures of her, may have raped her, and stripped her naked.....Stephanie Brown's case isn't the first.
-R