Here's a problematic the thing: consciousness exists (which is self-evident). Here's another problematic thing: none of the current theory predicts consciousness (at least, it seems that way; we probably don't know enough about consciousness to look for it in the model). So, until we have a general theory of consciousness (which may not be possible, in principle), any theory is incomplete (so long as we admit that consciousness is a thing, Descartes and all being a given in that case).
I'm not sure that consciousness falls into a special category no matter how special we humans deem it. Indeed many in the animal kingdom show self-awareness. We're probably being laughed at by aliens who think our 'consciousness' is cute. We could apply that reasoning to virtually all of our traits. I don't think anyone would necessarily predict that we ought to be bilaterally symmetrical instead of displaying 4- or 5-axis symmetry, but here we are. To me it seems we are just accidentally where we are without much cosmic direction... or utter cosmic direction with no intention, depending on your point of view. :)
D'Arcy Thompson explored in great detail the reason that bilateral and radial symmetry seem to be the only known body plans. But anyway it's a moot point, because there's a difference between self-awareness and body plan. One is a structural element, and the other is an inherent property (I think an apt analogy would be to compare a specific molecule with the charge on an electron; one is a possibility among many, and the other just is). I don't see why it follows that there must be a grand design, plan, or purpose, if we admit that consciousness might be a property of the universe. It only implies agency, not direction.