I'm quite sure it IS a commercial exercise and nothing more. But looking at why anyone would want to actually buy a signature bass... is it hero-worship, and the purchaser wants to support their hero, like a football fan wearing their team's shirt? Or is it because they imagine that the sig bass will somehow, by magic or osmosis, impart the skill, sound and success of said hero to the buyer?
Even though the buyer has banana fingers, two left hands, no musical aptitude and would be better off buying a kazoo?