You wouldn't be overjoyed that an artwork that you created is considered relevant to society in even some way 200 years after you were dead? The reason that this piece is able to be used this way is because it is unique and stands in stark contrast to the more formal, rigid portraits of the period. Something about the composition, the dress, the pose, it's casual nature speaks to our culture and to us as human beings. One of the most major issues any artist faces is that of relevance. Most are never considered truly relevant. Some are relevant in their time or after or even before. But the greats are relevant to all time, to all people. This is a success, not a slight.