In the comics, Odin is considerably more powerful than his son. The Allfather is capable of holding his own in battle against the likes of the planet-devouring Galactus and is capable of defeating characters like Thanos. As a side-effect of Odin's battles, galaxies have been destroyed - literally, entires galaxies have been blown up as mere collateral damage from Odin's fights. So, surely, if the universe is at risk in Thor: The Dark World, Odin should be getting his hands dirty and helping with the fight? Not only is it a waste of a very powerful character if his role is limited like in the first Thor movie, but it's also a waste of an incredibly talented actor in Sir Anthony Hopkins.