It was nothing reliable or game breaking.
The effect was not as great as to warrant a raid actively optimizing around this.
Yes, occasionally a perfectly lucky storm would, for example, refresh your WoC stacks.
But its main purpose and the main reason I already miss it is that we could have souls up for Bloodlust almost guaranteed.
10% dmg and double the traits during the early burst window when Affliction is at its weakest went a long way.