Re: "You ready for another Bout?"- The Thor/Chris Hemsworth Thread
Another possibility is that Asgard does not follow strict primogeniture, or at least doesn't have a strong established tradition for such ( which makes sense, given that near-immortals don't need heirs very often ). The ceremony could well have been more Thor's formal investiture as Odin's heir and successor, officially recognized as crown prince rather than simply being presumptive successor. Mind, his very first duty would have likely been "rule in Odin's stead as he enters the Odinsleep" either way.