I've been noticing a significant increase in the amount of players who build HP items and its not even limited to tanks/bruisers.I also find stacking HP more then compensates for the short comings of armor which doesn't offer no were near as much survivability as raw HP. This has resulted in the increased popularity of the bruiser which can capitalize early/mid game on the sustainability of an item like warmogs and snowball into a dominant position for late game.

AD and AP carries both suffer the most from the new meta, because they are unable to trade with bruisers earlier in the game who can out sustain and in turn deal more damage. Something is obviously wrong when your team consists of 3 bruisers.

AD carries are balanced around averaging 100+ cs every ten minutes (top 1% of players.)

Most players don't last hit this well. Bruisers are designed to perform with far less gold than an ADC. So if you can't last hit as a carry..... chances are the game won't last long enough for you to truly carry.

Armor provides survivability pretty damn well actually. They're not going to have Last Whisper and Black Cleaver early on, and the first 100 points of Armor are more potent than an equal value of HP (and it makes HP you buy more effective)

Riot is actually currently working on this - nerfs to warmogs and buffs to blade of the ruined king's on hit damage. But in case you haven't been around much this has been a problem since start of season two.