Despite the fact that the vast majority of plaguewrights are either benign practitioners of their own brand of esoterica or actively working for the betterment of their fellow man, the name sticks. It sticks because of the handful of lunatics who actually brew and unleash plagues. It sticks because of the visibility of the negative, because of confirmation bias itself.
In the end, the only way to move forward is to walk away from the name altogether. The apothecary is a specialized plaguewright who gives up a large portion of his ability to do harm in exchange for additional support and healing options. Creative physicians, benevolent mad scientists, and the like fall under the umbrella of the apothecary. Do you?