Just don't bother going tanky anymore, either go glass cannon or semi-tanky with % damages
You will never, ever, be tanky in the current state of the game.
A vi with a botrk and the warrior's enchant item (not even devourer's, lol) killed my 150 armor -4K hp elise in 3.8 seconds, without LW, solo.
I don't even want to know how fast I'd die if they didn't have a terrible ADC and crits from IE were part of the mix.
You either kill or get killed right now.
The new stat growths must partially also be responsible for this.
In short, unless it's Maokai or Alistar, don't bother investing heavily on defenses, just pick items that have both offensive and defensive properties(BC,hex/maw,botrk,etc) and a randuin's. (or a warmog's if you are sieging often)