Slavery was abolished. People still use wheelchairs today.
Are you saying you would rather have no one in comics, no one in fiction of any kind, no one on TV have any disability? Have the cultural world completely ignore disabilities, pretend all the people who have them don't exist? Or maybe pretend that they don't exist in reality, either? Not have laws ensuring that buildings be accessible for wheelchairs? Get rid of all the braille in the world? Stop teaching sign language?
Equating the depiction of Barbara Gordon as needing a wheelchair with slavery that way is poor logic. That doesn't mean that there are no stories to tell about slavery, but to make a character of today's world into a slave out of nowhere, particularly an African American, would be hurtful and demeaning.