The argument Ive uses is that when the iPhone first came out and smartphones became a mass market consumer good, people needed the guidance afforded by skeumorp

The argument Ive uses is that when the iPhone first came out and smartphones became a mass market consumer good, people needed the guidance afforded by skeumorphism to adapt to a touch-screen environment. Now that pretty much everyone and their grandma has had a few years using a smartphone and knows their was around a touchscreen, the usability benefits of skeumorphism are no longer as valuable when compared to the aesthetic concerns. Thus, flat design.