Your post demonstrates a excellent understanding of the matter. Many of the points you bring up are issues that I have been wrangling (dealing) with. As it stands, and probably well into the future, the process I use is only good for a parallel, non-attenuating light source. The Sun.
It may work for sunlit interior shots (my current experimentation) but would never be capable of inverse square attenuation, global illumination, etc.
Regarding contrast, the use of hatches for shading and shadowing does allow for post render balance adjustment by changing the Layer colors. Similarly, the isolation by layer allows tweaking Line-weights and color for all linear vectors.
As you alluded to, there are issues with non-planar surfaces so, like the early days of rasterized renders, all curved surfaces are pre faceted and this vector render process treats then like all the other planar surfaces.
I’m not sure what the goal is. For now, I’ll just create a few more views of the current model, have those views surround the standard 2d floor plans, and put it all on an ARCH E sheet. I may shop that around to the local architectural firms. Perhaps get a little side work out of the deal.