Aura based decks at this level of the game is quite rare usually due to the nature that they must enchant a permanent.  Cards like Rancor and Moldervine Clock were played because of there ability to be reused later in the game after the creature had died.  Other cards like Pacifism effects have been used before in the past.  This usually leaves an opening for an opponent to cast a removal spell to deal with both the aura and the permanent, leaving you at a disadvantage.  

Since Magic R&D moved from creatures with Shroud to Hexproof, things have changed.  No longer are they able to gain card advantage from a single targeted removal spell.  The basis of the two decks in the finals of GP Atlantic City started with a deck from PT Avacyn Restored:

I tagged this deck after I saw coverage of PT Avacyn Restored.  I knew it had potential.  The problem was the this version ended up being to slow in the original metagame of Zombies (both Br and Bg versions) at the start of the RTR Standard season.

So what changed?

The designers of the current standard deck were paying attention to the Modern format and noticed a standard legal card that changed the speed of the deck from slow to hyper speed:

Ethereal Armor, a common Aura from Return to Ravinca had been seen as a late pick around draft tables everywhere.  What this card does is not only on offense (even thought in a deck like this Modern brew it can kill you on turn 4).  In the standard format, the brew can play amazing defense with a Geist of Saint Traft enchanted with Ethereal Armor and say an Abundant Growth in play.  A 4/4 Hexproof First Strike is a nightmare for most of the aggressive decks currently in the field.  Drop a Spectral Flight, a Rancor, or Silverblade Paladin down and your looking at dealing 11 to 12 damage in a single swing.

"Two magi could trade spells all day and never crown a victor. The real battle is not one of power but of will. If your confidence breaks, so too shall you." —Venser

Bradley Reeves
@Yawgmothswill