That is a very dismal view of America, I hardly think we are anything special down here where it happened when I was 8.
But what did NZ gain from it compared to all the trouble they had to go trough?
All the math books in school had to be replaced, all traffic signs and road signs altered or replaced, the stress with elder people, all the legislation that has to be changed and and and.
You were at the right age: You learned to handle metric measurement at the start of your school life. Never learned to calculate with fractions of inches. But I think that people that used the old system for over 30 years or so were not that happy with the change.
We changed to Euro little over 20 years ago now. There are still some people who calculate the amount in Euro first into the amount of the old Dutch gulden before they make financial decisions. It doesn't come smoothly with everybody.