Like many fashions throughout time the Elizabethan collar or ruff had its origins in a display of wealth. So called Elizabethan (to state the bl44din obvious) because it was seen predominantly in the reign of Elizabeth 1 of England. As has been said previously you would need a lot of spondulics to purchase and launder these, sometimes needing several a day. They display a fashion accessory that you cant do much manual work in...so an outward statement to say 'look I'm a lazy sod'
Also in the same era were worn slashed sleeves to display silken undershirts which also showed wealth, and which in turn the undershirt was to have slashes in them also to outwardly say 'look I've got more spondulics than you plebs'.
Now the cod piece takes on a whole fashion statement all of its own (check out the size of Henry Vlll cod piece. What these said was 'Virile, Manly, Mighty and could be easily untied if you got some action pending' but thats a whole different kettle of fish (or cod).