Eh, Gold is shiny, look into history and you'll find that is the number one reason it was utilized as currency backer. It helps that it is rare and hard to reproduce thus controlling the actual item had strategic value. But again, we put that value there solely based on greed for gold.
I agree about the conductive properties being used in tech advancement thou, but when the idea of a currency system first came about that wasn't at their forethought. For example, what would the world have been like had gold not been as rare as it is?