That's precisely why I call it an overreaction. Kate vanished as quickly as she appeared, not to be spoken of again until recently, whereas Batgirl continued to appear in a bunch of other publications (though admittedly none of them very good), joined the Outsiders and eventually even got her own series' back (though again, not a very good one). This is the kind of knee-jerk fan reaction that serves no purposes other than to make very fan look bad.
Also, it occurs to me that "Lezbo" seems to be one of the few hateful slurs you can still get away with without fear of recriminations, and that bothers me.