Today, we didnt need resist because all the damage is mitigated by by armor.
So why do we need resist in the first place?
The only logical thing why we now need resist is because the armor are now changed that you needed to additional Resist.
Unless Resist is for those annoying CC, then we have another kind of resist,
Resist Fear, Resist Frozen, Resist Bleed, Resist Stun, Resist Burn.
For elemental resist, i dont see how we might need a elemental resist with current model where armor cuts all the damage.