I can think of a couple of parallels to Levine's work that make me feel more comfortable about it.
1) the use of "sampling" in a lot of recent music, wherein samples from another's work are incorporated in the more recent work. Where it works well, it is because of the contrast and context between the old and the new; and
2) Andy Warhol and his many images of the familiar or even the mundane. Warhol's "art" is as much in the implied comment about those images, as it is in the images themselves.
I don't think there is any dispute that Levine's work is photographic - it is much more like a collage of one. It truly does not have any value, unless you do know the title, and do know something about the purpose and context of the piece (not the original, but the object that is created by copying the original).
I also think that the artistic medium she uses isn't the medium of photography, but rather it is akin to written social commentary.
It is a type of "performance art" that is highly analytical, and thus likely to appeal to relatively few people, but to say that her process (i.e. the action of creating a copy for the purpose of examining the relationship between originals and that which is created when one makes a copy) is incapable of being a form of artistic expression, is somewhat too limited.
I am not in the market to buy one, but I think they are thought provoking and do have value.