Why was Johann Wolfgang von Goethe made a noble in 1782?

Johann Wolfgang von Goethe was ennobled in 1782 primarily due to his expanding role in the administration of the duchy of Weimar.1

In 1782, the chancellor of the duchy’s Exchequer departed, and Goethe agreed to step into the role for two and a half years. This position effectively made him the prime minister and the principal representative of the duchy during a period of increasingly complex diplomatic affairs involving Duke Charles Augustus. Because this role required him to act as the primary official representative of the state, it was considered essential to raise him to the nobility, at which point he became known as "von Goethe".1