Walk radical wrapping around -
走 pictures a person leaning forward in motion.
越 is to leap or go over, an exaggerated form of walking, so the radical fits directly. Joins the locomotion family:
起 (rise),
趟 (a trip),
趋 (head toward),
赶 (rush) - characters where the bottom-and-left wrap is
走 and the action is locomotion.
