Of course, if you want to "bring physics into it", none of the armors would likely protect against any of those things. Let's see:
Lightning? Metal armor conducts that stuff.
Fire (fireball, dragon breath, etc)? Again, metal armor heats up, so you'd keep taking damage from the fire long after it was gone. Plus the fur/cloth/leather bits would burn.
Ice? Hey, metal conducts super-freezing cold, too.
Physical attacks by massive creatures (giant's club, mammoth, dragon)? Don't care how strong your armor is, it and the spine holding it up would crumple like an accordian.
Fantasy games are inherently unrealistic and irrational, from a scientific point of view.
And, again - I'm fine with that. I'm happy playing an ideaized game (straight/white teeth; clean hair & skin; being able to take a sword blow without falling to the ground in crippling pain/getting infections that cost limbs/taking months to heal; men being bulging oiled muscleheads/women being curvy models) rather than a "realistic" one (rotting yellow teeth; grimy hair & pockmarked skin; possibly dying to any random dagger strike no matter how tough you are; people being sickly/ugly/etc).
Personally, I've never been much of a fan of "low fantasy" (scrabbling around in the dirt & mud, dealing with things like struggling to feed yourself and avoid scurvy & the pox... not nearly as interesting as heroic adventuring). And I've no interest whatsoever in a "medieval life sim". Nor, do I imagine, do most people outside European History departments at the university.

