Commons does, however, allow scans of 2D public domain works that have "scarecrow" copyright claims in light of Bridgeman v. Corel (which ruled that such scans/photos can have no copyright in the US due to a lack of original creative content).

Commons doesn't accept 2D photos of 3D works because these photos' lighting, positioning, etc. choices can give them original creative content. But a 3D scan isn't likely to contain such creative choices. It may be annoying to make one, but the US does not have "sweat of the brow" copyright.