By Tobias Carroll Some paintings commissioned by the United States government have sparked a generally positive, even laudatory, public response. Consider Kehinde Wiley’s portrait of Barack Obama, which drew an abundance of viewers to the National Portrait Gallery and has prompted thorough analysis by some art writers. It’s one example of a work of art that transcended its official function. On the other side of the spectrum, you have a more stylistically restrained work like Howard Chandler Christy’s 1940 painting Scene at the Signing of the Constitution of the United States. As a new article…