Fist bumping evidences humans as being trapped into mundane reality. Fist bumping also establishes the social nature of the human collective. The tenuous nature of existing in the mundane can be eased through social gestures. The majority of people could not explain the why or wherefore of (their) engaging in normalized social actions. I am not adverse to touching but I do feel that a visual acknowledging, in many cases, is more than sufficient .
Ab-Sutra Wellness and Fitness 