A lot of it is survival bling, but some of it is useful. I took a course with the Sierra Club about 10 or 12 years back, and they had SERE instructors guest lecturing at the graduation campout. I remember one particular piece of advice they gave: "You can never have too much cord, too many knives, or too many ways to make fire".

It's also just plain fun to play with. It's the modern day version of sailors' fancywork knots. I've made the usual hatbands and zipper pulls out of it. I tried to make a belt out of it, but it was too thick and ended up using 4mm macramé cord (160 ft worth of clove hitched cord).

If you're looking for actual useful (easy to pull out) plaits for survival bling, look up a double chain sinnet. It's also called a bugle braid, and requires an obscene amount of material (6-12 in/in).
http://www.free-macrame-patterns.com/bugle-braid.html