I've wondering this myself - specifically, why did Switzerland move away from the gold-backed Swiss Franc.

A little research reveals this (from Wikipedia):

The Swiss franc has historically been considered a safe-haven currency, with a legal requirement that a minimum of 40% be backed by gold reserves.[17] However, this link to gold, which dated from the 1920s, was terminated on 1 May 2000 following a referendum, making the franc fiat money.[18][19] By March 2005, following a gold-selling program, the Swiss National Bank held 1,290 tonnes of gold in reserves, which equated to 20% of its assets.[20]

...but this can't be the whole story. Anyone got more?