By this logic, why is food a resource? What does it add to the game? As far as ANYONE can tell, its meaningless content. Anyone can make it. My nation is an Ireland sized diamond off the coast of Brittany ENTIRELY in the Atlantic Ocean and produces food.
Running out of food is moderately annoying but not particularly crippling or concerning. So what's the point? You thought food was a necessary must have thing for... logics sake? I went 16 days without food once Alex. I'd have been dead in 3 without water, so that don't hold up too well either.
Water as a resource could also, ontop of dealing incredibly severe penalties for running out, be required to run nuclear plants. Yanno, like it's require to do in the real world.
Infact you could add water as being necessary for almost every improvement in the game. There's not a mine, military installation, or commercial structure in the entire globe that does not in some way require water to function. You'd have no commerce, power, mines, manufacturing, recruitment or military. Your units would act like you had no gas or munitions because they like everyone else is busy trying not to die of dehydration.
Running out of water therefore would knock out pretty much everything you have except... what? Windmills? Say goodbye to commerce, say goodbye to population, why, running out could even start eating into your age bonus. Fun Fact: Shortages of super-critical resources like water cause people to frick off elsewhere and they usually don't come back anytime soon.
So, now that i've gone on that tirade, back to food. What does food add to the game again? Because i just made this hypothetical water resource relatively on par with water in the real world in terms of it's presence and usage being super-critical and absolutely necessary. Running out of food is moderately annoying, running out of this water would put your nation into a coma.
Somebody ring the bell i think we have a clear winner here.