I'm now able to load materials from GLTF files. These can use external textures or they can use textures packed into a GLTF binary file. Because we have a standardized material specification, this means you can download GLTF files from SketchFab or Turbosquid, and your model materials will automatically be loaded, all the time. There's no more generating materials or messing around trying to figure out which texture is the normal or specular map. An extension exists for DDS texture support, fortunately.
Here are the preliminary results.