Yes WAR has the shortest recast on their defensive abilities, but that does not mean IB is disregarded, it's one of the most reliable mitigation tools offered when playing WAR.
This is basically what managing the stacks is about, sometimes you need Inner Beast, other times you don't, sometimes you use it just to be safe.
This all depends on what content you are doing, who you are doing it with, and how well the fight is going. Different circumstances means different adaptations might be necessary.