Well, Gray, you make a plausible question here, but I really don't think you've shown you're qualified to answer it. I wish you would, but you don't. The contents of the thread, at least, seem to be simple expressions of opinion without much to back it up. Let's remember something you always forget, which is that facts are your friend. Also recall that when I mentioned Apollonaire, a demonstrably greater poet than you or me, who invented this form, you said bah humburg it's only performance art. A rather laughable statement, since Apollonaire did not perform in the sense of performance art at all. He was simply too French for that. John Yamrus, who can't really be a fairly close ally of yours on this point, created a witty piece of concrete poetry that you likewise dismissed as performance art. This ignores the fact that the box made by Yamrus cannot be performed. Again you did not use reasons, other than that the sounds are not altered by the shape.
Okay, with that background let us engage in some analysis. We can use the Yamrus piece. Recall that a poem is defined, and you have approved this definition, as a collection of words that evokes an emotion in the reader that is different than the meanings of the words themselves as put down on the page. Clearly the sonic qualities of the words are of much import, which is why all poems should be read when being understood. As the Yamrus box illustrates, though, the simple meaning of the words can be amplified, bent, made ironic or any number of other things by a good shape that they may make. Obviously, therefore, the shape of a concrete poem can lend to and influence the evoked emotion, which means that a good concrete poem is in fact poetry, contrary to your unsupported assertion that it is not. I don't particularly care for concrete poems, except when they are witty and well constructed as is Yamrus's, but you are simply wrong that they are not poetic.
Ollie, I think Yamrus did intend that very level of irony. Which proves my point, by the way.