Cloth cord is what wiring looked like when it wasn't meant to hide. Before the smooth plastic insulation we take for granted, the cord that carried power to a fixture was wrapped in woven cloth, and it hung in plain sight. What started as necessity became a look, and cloth cord is now a deliberate choice rather than a leftover.
From necessity to detail
The reason for it was practical. Early insulation needed a protective outer layer, and woven cotton or rayon over the conductor did the job, in an era when running wire openly, along a wall, down from a ceiling, was normal. The cord was part of the visible fixture, so it had to look finished. A bare-bulb pendant or a simple shade on a length of cloth cord looks intentional, where the same fixture on modern plastic cord looks unfinished. The cord is the detail that turns a plain fixture into a designed one.
There's a safety point worth being clear about. Original cloth cord, eighty or ninety years old, is not safe to run; the insulation underneath has dried and failed. What you want is new cloth-covered cord, made to look like the old but wired to current standards. The look is historical; the wiring is not, and shouldn't be. We build and stock cloth-cord pendant kits with new cord for exactly that reason.
Salvager's Note: Never run original cloth cord. Ninety-year-old insulation has dried and cracked, and it's a fire risk. New cloth-covered cord gives the identical early-electric look wired to current standards, which is the only safe way to have it.