Without passive abilities, it becomes impossible for Werewolf players to keep 100% uptime of Werewolf Transformation. From what I can tell, very few Werewolf players build to utilize both of their forms — generally speaking, they pick their sets, passives, and CP around staying in Werewolf form the entire time.

There's no doubt that if Werewolf was added to Vengeance rules, it would lose all the passive abilities, including Call of the Pack and Blood Rage. I think that in this instance, the transformation should be a toggle, which would actually be to the benefit of Vengeance itself as it would remove the need for the timer, the value of which is constantly changing. This would make Werewolf tolerable to play under Vengeance rules, since it's incredibly unimmersive/disruptive to lose form in the middle of combat and have to grind Ultimate just to get Werewolf back for another 30 seconds.