[michaelt]

Partly this is a fun exploration of creating art in an unusual medium, much like a photographer might experiment with antique lenses, unusual film formats and suchlike.

But also, although a lot of modern 3D renders are highly realistic there are certain levels of realism they don't bother to pursue, for both computational efficiency reasons and the fact a lot of users don't want them.

This chap had to simulate a lot of light rays, because only a small fraction of them ended up on the imaging plane. You can achieve effects like bokeh adequately with much less render time by using a conventional blender camera and a blur proportional to the Z buffer.

Meanwhile things like film grain, the corners of the image being darker, spherical aberration, chromatic aberration, parts of the image out of focus, lens flares etc aren't what everyone wants for their image.