But Iron ore was the reason why Hitler invaded Norway and Denmark, to safeguard his supply of Swedish iron ore.
I was being sarcastic.
Japan had severe iron shortages, iron, along with rubber and oil, was the reason the conflict with the US was inevitable in WWII.
Germany had some rather large problems in getting enough iron in WWI, and had to request iron (and other metals) from the population in form of pots and pans.
Even the UK (in WWII) had iron shortages, which is one of the reason the Mosquito was made from wood.
Edit:
I would prefer a solution were you could build more unit per iron resource as the game progressed (2X with steel, 3X with electricity, or some such), but that certain units still required the resources.
This way the iron resources would still be valuable, and a cause for conflict.
But I suppose that this, along with the near useless bonus resources, is something for a mod. To be honest, what I'm giddy about isn't CivV, but CivV with mods (CivV + Rise of Mankind, nomnomnom!).