Enchantment was weaken due to Odin's death. Hence enable Hela with same Asgardian magic to destroy Mjolnir.
Odin force was not fully Thor force which i believe still resides back to asgard to be chosen to wield it.
Hela also in movie derives her power from Asgard.
They said the same for Thor. Which has made me wonder what happens to Thor's powers now that Asgard is gone. Odin's comments seem to make me think that they will be what they are but it is left fairly open at the end of the movie based on the dialogue.
It is fair that Odin dying may have had some impact on it, but not entirely sure it would have mattered too much. She was also familiar with the weapon. And the whole power of Thor and worthy things were added later.