Blackout.
It was a huge driving force in today's sounds. If you don't remember, 2007's hit songs and albums were very diverse and ranged from Irreplaceable, Big Girls Don't Cry, Bleeding Love, Umbrella, Hey There Delilah, etc.
After Blackout, basically every big song (especially in later-2008 and 2009) was electro dance or had elements to it and almost everyone was checking on vocoders, auto-tune, and synths.
We're still feeling the effects of Blackout today. "Freakshow" was basically the first pop song by a major pop singer to heavily feature dub step and just look at 2011-2012.
Rated R was certainly very good as an album, but the songs and the album altogether failed to create any real lasting shifts in mainstream music.
