The "erased technique" has emerged as a very popular design element. The rug designers deliberately plot areas of knots to make the rug look as if there is worn spot.
Originally it was thought that this might lend gravitas to the room, suggesting tradition and durability. Later the erased technique came into its own and designers started incorporating it where they felt it would be the most interesting and fun.
This color fits nicely into black and white design which we are seeing a lot of lately.