It has been established that the Fantastic Four's powers reinforce each other, that if one or more of them is missing for a long long while, the remaining ones powers start to weaken. Movie Johnny may have been alone without his other FF for too long, resulting in a loss of abilities.

They did this before with Alpha Flight, had the first issue with all the group., had intervening issues spotlighting individual , brought the group together again, and killed the leader.