The 1980s was a decade of makeup, fashion and hair rebellion. Everything had to out-do everything else. Fashion was brighter and more accessorized, makeup was applied with a heavier hand, and hair was layered and larger-than-life in every sense. Haircuts, no matter the length, were heavily layered and curled in perms so that volume was the highest priority.
Feathered styles were all about the layers, whether they were long or short. Feathered styles were big in the 1970s, but by the 1980s, many women cropped their hair off into shorter cuts and bobs, but kept them feathered for ultimate volume. Their hair may have been short enough to not touch their shoulders, but it was still large enough to create a cloud of curls around their heads.
Long shags were extremely popular in the 1980s, especially ones that were also permed. Hair that was long and one length permed tended to create a gigantic triangular shape that had lots of volume on the bottom, but little up at the top. This is why shags became so popular. Short, even layers all over the head allowed the perms to create larger-than-life curls that were big and voluminous all over the head, which was quintessential 1980s style.
While mostly men rocked mullets in the 1980s, a lot of rebellious women, especially those in the punk or rock 'n' roll scenes, sometimes cut their hair into feminine mullet styles that were razor-thin and layered. They were cut shorter and layered up front, but long and layered in the back.