If someone made a friendly python GRASS wrapper that would let you use GRASS function in a pythonic manner with numpy/rasterio/fiona/shapely data i think GRASS usage would increase massively.

Yes, this is it for me too. Whenever I have a huge vector dataset I need to clean up, I would use GRASS simply because it is topological, and can re-interpret, fix, manipulate vectors efficiently and valid, as a single layer entity. Even though PostGIS added topology, I have not been able to figure out how to do the same manipulations, or achieve the same speed.