Dark ≠ Deep

Peter Steinfels questions reviewers who praise the new Harry Potter movie for its darkness:

Dark means serious. Dark means shadows. Dark means not evading the sad and inexplicable complexities of life—or even worse. Dark is grownup. ... Profound = deeper = darker. I understand the subterranean metaphor. But could we turn it around? What of the image of light? Though darkness is inescapable in our faith, could we write, even if somewhat paradoxically, that a poem touched a deeper, brighter place than any before it?