Because you couldn't find a meaningful way to assign Chinese characters to represent each possible combination of two of {left, right, down, rotate}, which is w

Because you couldn't find a meaningful way to assign Chinese characters to represent each possible combination of two of {left, right, down, rotate}, which is what the previous hex encoding mentioned can do, let alone do better. (As a novice, I can think of relatively reasonable ways to represent some of them, but no way to account for order. For example, "down left" could be "southwest" via the Zodiac animal, "left right" could be "horizontal", and "down rotate" could be "screw"... but that wouldn't help with "left down", "right left", etc.)