Where exactly did Blizzard say he needed them? Because it was not in Chronicles and I can't recall an in-game source saying that either. As for Helya, the only reason she acted that way was because she was forced to do things against her will by Odyn. With nothing suggesting he had such a right. Other Titan Forged ignored him and his tantrums before. And the only real harm she incurred against Azeroth itself is indirect at best, if one was to assume Valarjar could have prevented some harm that has happened. Which is speculation.
That's bound to happen eventually (and sooner rather than later) given Blizzard's stark ineptitude at managing their lore. But that'd require an actual conflict of lore, where the rule that newer lore trumps older lore would actually apply.