Public art, monuments, public architecture all have gradients of community-accepted appropriateness and are judged accordingly. It is true that there has often been controversy surrounding the role of the general public in these aesthetic choices. Artwork has many afterlives. Once the artist and the community contemporaneous to them are gone, the social transaction between them is moot, yet the tangible art object remains. Others can project meaning onto this object in ways that are unforeseen.
Ethical guidelines evolve and moral standards change.
Some works of art are completely misunderstood by subsequent generations and therefore enter into an ambivalent relationship with the original ethical impulse that guided the artist in making and presenting the work. I would tend to exclude the potential for drawing meaningful ethical conclusions about art dating from other periods, if only because it seems to enhance the ways in which misunderstanding can occur. I have no illusion that this discussion represents a final word, but can only hope that it does help set the stage for further discourse about ethics and art. It is where I feel I can start from. While I expend no effort whatsoever condemning works that I find to be ethically un-engaged, for, as I've argued, these are loaded and nebulous ideas, I am always pleased to find works which somehow manage to satisfy the ethical impulse.