How about, instead of nerfing armor, we buff magic resist?

Currently, there are two items that give 100 armor: Frozen Heart and Thornmail. And they are dirt cheap for the stats they give. What item gives the most magic resist? gives 70 magic resist. That is 30 less than the highest armor items. And, this item isnt even in summoners rift. Which item gives the most magic resist in SUMMONERS RIFT? this...thing. the item is trash, anyways. unless you are running a siege comp or something. the active component is just a waste. you're lucky if the void spawn even reach the structures, let alone damage them.

Why dont we make a magic resist item that gives 100 magic resist? Nerfing armor just seems unethical.