From my own point of view with the little experience of working with LDraw as a software developer I have, I can say that, mostly, I don't see much things in the approach.
On the point about quads - with the way spec allows using them them, not much ambiguity can really arise.
About normals - mostly, they can be easily calculated using the outlines, using them to either separate (normal outline) or merge normals (condline). One thing tho is really bothering me, and that is how heavily LDraw relies on geometry color for making the printed parts. It really is not a problem for flat parts, or when you are not using any lighting aside the ambient light. But in pretty much all other cases it causes very ugly calculated normals, so, the way parts like minifigure heads are done should be preferably rethinked
In the same bin go, by the way, marbled parts. For them I think the textures can be applied - by defining a META command that uses a black/white texture as a map for where to put the color being mixed in
On the point about quads - with the way spec allows using them them, not much ambiguity can really arise.
About normals - mostly, they can be easily calculated using the outlines, using them to either separate (normal outline) or merge normals (condline). One thing tho is really bothering me, and that is how heavily LDraw relies on geometry color for making the printed parts. It really is not a problem for flat parts, or when you are not using any lighting aside the ambient light. But in pretty much all other cases it causes very ugly calculated normals, so, the way parts like minifigure heads are done should be preferably rethinked
In the same bin go, by the way, marbled parts. For them I think the textures can be applied - by defining a META command that uses a black/white texture as a map for where to put the color being mixed in