If you have multiples of anything, you have the possibility of repetition. Repetition creates pattern and also unity. Put anyone in a room with a pile of similar objects and say, 'I want a pattern by 3 P.M. or no dinner.' Anyone would come up with a design. It is easy, fun and available to anybody. Most people just don't have the nerve.
The first cause of waste is probably even buried in our DNA. Human beings have a need for maintaining consistency of the apperceptive mass. What does that mean? What it means is, for every perception we have, it needs to tally with the one like it before, or we don't have continuity, and we become a little bit disoriented.