To make an LF lens retrofocus enough to make a significant difference to the evenness of illumination, it would be impractically big and heavy. Compare a retrofocus and a non-retrofocus 20mm lens for 35mm format, and remember that the mounting/barrel is a much greater part of the total weight in that format than in LF lenses.

A good LF retrofocus WA lens could easily be made, but how many would like a 75m f:8 lens weighing 4 kg?