A central aesthetic principle in Japan is simplicity, but it is different from simplicity in the West. Let me explain the difference by comparing cooking knives. The knives made by the German company, Henckel, for example, are well crafted and easy to use because they are highly ergonomic. The thumb automatically finds its place when you grab the knife.
Japanese cooks who have special skills prefer knives without any ergonomic shape. A flat handle is not seen as raw or poorly crafted. On the contrary, its perfect plainness is meant to say, “You can use me whichever way suits your skills.” The Japanese knife adapts to the cook’s skill (not to the cook’s thumb). This is, in a nutshell, Japanese simplicity.