This occurred since the JMS run and followed up in Fractions run. Thor is now not afraid to alter the 9 Worlds. Previous to that, Thor left it to Odin the All Wise, the All Powerful, to alter the 9 Worlds and control them. But now that Thor, Baldar and the All Mothers have tasted the ability to change things, Thor isn't afraid to challenge Odin in the administering of the 9 Worlds anymore.
Odin had always been the one to control the outcome of the 9 Worlds, and just left Thor as the Champion of the gods, except for that one time when Odin used all the resources of his realm to face the Celestials, and they beat him like he was a bug. Why didn't Odin change reality like he did when he forms the 9 Worlds out of nothing? Why did the Celestials only come to Midgard and not the other 9 Worlds? With Fractions revelations that Odin can manufacture anything he wishes, why didn't Odin wish the Celestials into defeat, or Galactus for that matter?
But now that Odin has to baby sit his brother Serpent, Cul, Odin does not challenge what the other gods do in the heavens. The other gods are changing whatever they like now in the heavens and Odin has no recourse to stop it.