Simple is hard. If someone can't tell the difference between a beautifully rendered minimalistic design and something generic that just happens to lack eye-candy effects, that doesn't lead to the conclusion that flat is easier to accomplish; it just means that person can't tell the difference between good design and bad design. A trained eye will pay attention to proportion, balance, color relationship, (a)symmetry, etc.

From Bauhaus to Braun, Frank Lloyd Wright to I.M. Pei, architects, artists, graphic designers and engineers have been studying and applying these concepts. Lost on many, but still perfectly valid.