Natural rope can leave abrasions on the skin and 'hair' splinters. Burns are easy to create with hemp and manilla rope. Let alone a full medical examining table and stirups. Natural rope's disadvantages are that it swells when wet. More so, it has a realativly weak load ratio for it's diameter.
Natural rope has a nostalgia many people are attracted to.
Man-made rope, on the other hand, has far different properties. First and foremost it is vastly stronger than natural line. Artifical rope is not damaged by water, immune to rot and mildew, and it's resistant to common solvents, gasoline, and has an impressive load capability. It's ability to absorb shock-loading by stretching makes it ideal for climbing, suspending, and 'comfortable' restriction. It is best suited for situation where slackness could be inconvienent or even disasterous.