I found a 1080p 4:3 PC screenshot and nearest-neighbour downsampled so the 3D matches the 2D background pixel grid.
Then I manually overlaid the 'high'-res PC speech box.
Oh, that explains it. Really, this is how the character models are meant to be presented. Lightning-aside, they don't stand-out that much, and the level of detail is mostly consistent with the number of pixels.
A Steam version mod that affects resolution contextually -- ie. renders menus and 2D assets in HD, but 3D elements in a lower resolution -- would be nice.