Key quote from the Quora link:

> (1) Long, thick penises were considered--at least in the highbrow view-- grotesque, comic, or both and were usually found on fertility gods, half-animal critters such as satyrs, ugly old men, and barbarians. A circumcised penis was particularly gross. (2) The ideal penis was small, thin, and covered with a long, tapered foreskin.

This is in conflict with your idea that they are just 'average', rather than idealized.