The "rap" of an artist

In the comments of this post, Mike J says this, and I hope he forgives me for copying:

By "rap" in this case I mean the spiel that an artist develops ostensibly to explain what it is they're doing. Often, this functions as a sort of meta-communication: they're signifying more than they're saying. The hidden message might be "I'm intelligent," or "you can't understand this," or "I deserve to be taken seriously." Often, too, the "rap" tells a viewer how to feel about the work, either co-opting the viewer's own unruly responses or suggesting a framework for understanding and acceptance for those who won't bother to decide for themselves.

I had a very interesting experience with this early on. Joe Cameron curated a show of works in progress that had, I think, six or eight "openings," week after week. Each week, each of several artists would show how their work was progressing and talk a little bit about it. A fascinating experience and one that was important to me.

Anyway, one of the experiences of that show for me was that one artist, who had strong work, actually made her work seem less strong to me because she had a weak rap for it; another artist actually managed to make relatively weak work stronger because he was able to talk about it vividly and brilliantly. It didn't change my absolute impression of the work--hers was still better than his--but it really did have an effect on my perception. Even though I was perfectly conscious of how my perception was being manipulated. I've never forgotten that.

I think this is highly interesting.
Some people seem to like, nay, to demand, that an artist not only must be able to, but should explain his work, precisely and at length.

I am not sure, there may be cases where this is an enhancement of the work and experience, but I'm very hesitant about it.

For one thing, he might inadvertently belittle his work. For example, I read an interview with David Bowie where the journalist asked about meaning of a song (I think it was Bus Stop), and Bowie said "oh it's just a silly little song" or words to that effect. What if the listener had a great, uplifting experience from a song/painting/book, and the author pulls it down like that?

For another thing, if art can really be explained in words, why have art at all? Can you explain Beethoven's Fifth? (Do you think Beethoven could? If he could, I doubt I'd want him to.)

For a third thing, contrarywise to what might be reasonably expected, I think often the artist does not understand his own work a lot better than any other member of the audience. He may be the artist, but he is also just another audience member.
For instance, my drawing the Swan And The Swine was done very quickly under great time pressure, for a poster for a theater/music show. (The original was not colored.) Yet it was very successful, and many people later asked me: is it a tree or a mushroom cloud? And all I can say is 1: I only thought of it as a tree when I drew it, but 2: it clearly also could be a mushroom cloud, and I clearly could not have drawn it in any other way, so... even as the artist, I must just have the humility to say 'what the bleep do I know'?...

And continuing the third point, it is not hard to find many books or songs written "just for money", but which turned out to be great and significant work. Clearly the art can be much bigger than the artist, and I think it's hubris to assume should know all there is to say and think about it, much less try to nail it down for others.

Which brings me to the fourth point: it seems to be very hard to say anything at all about a work without interpreting it to some degree. And by doing so, you limit or block other interpretations. Which is a crime, again because no single person can see the whole of Art.