Over the past couple of weeks, a lot of arguments have been offered for why an original work of art should never be altered by anyone but the artist. I think the arguments can be generally categorized as being based on justice (e.g., altering misrepresents what the artist said, or offends against his dignity, or interferes with his right to participate in the cultural conversation), on prudence (e.g., altering results in a loss to culture, altering is an act of hubris), and on art (e.g., altering interferes with sub-creation and the mediation of a particular insight into truth and beauty).
I answer that, an artist is an artist insofar as he actually makes things (either things generally, if you're defining "art" broadly, or specific kinds of things like paintings and plays, if you're defining "art" narrowly). Justice is the virtue of giving to another his due. We can only talk about justice toward artists, then, in terms of the things they actually make.
And since the things they actually make are particular things, we can only speak of justice towards artists-as-artists in particular terms -- which is to say, in regard to works of art that have particular qualities. Since, given any set of particular qualities, an artists could make a work of art that lacks this set, it follows that there are no completely general principles of justice toward artists-as-artists.
That said, the artist's vocation to reveal beauty and truth in his work must be taken into account in making prudential decisions involving works of art, be they decisions to apprehend, to display, to conceal, to engage, to alter, or to destroy. The value of a work of art is to be judged according to different standards than those used to judge the value of, say, a bridge or a financial statement.
Given all this, I think the arguments against alteration can be reclassified into these three groups: romanticized but specious claims of special rights for artists; asserting various implications that follow from a work of art possessing certain qualities, which necessarily presupposes some artistic and prudential judgment of whether a particular work possesses the qualities; and insisting that the implication following from a work of art possessing certain qualities be applied to all works of art, for fear that an improper judgment might be made in a particular case. Note that none of these groups contain a valid, general prohibition on altering an original work of art.