It's quite odd. I know they kind of rushed with the figures, so maybe they meant to create real textures, and never did. The thumbnails show colors, but the material files don't create that color.

The materials do work. If you change the color, then apply the material, it turns them back to white.

I think the only reason you'd use the material files for Sydney's clothes is if you changed the texture, and wanted to restore the original. Because the clothing, textured or not, loads with whatever textures it has.

And it's something not many people have noticed, because, like you, most of us use V4 instead.  :-D