@shortstories Because it was turned into an insult and they know, it's used as an insult. It's the same story with the words: Retard, imbecil, moron, ect. They used to be medical terms with real meaning behind them, but they were hijacked by people outside the profession and degraded them into everyday insults.
Any word used to refer to a group of undesirables will take on a negative connotation.