Hmm. Your dashed lines suggest volcano chains which are not parallel to the more recent Hawaiian trend. If the current Hawaiian trend is determined by plate motion alone, how is this possible? (Esp. since those other island trends seem more parallel to the older Hawaiian one, which the article attributes to migration of the hotspot)
Could also have something to do with the composition of the rock over the hotspot at any given time. Perhaps the rising magma follows the easiest course upwards, which may not always be the most direct route.