I can't say as I found Orcs an interesting expansion theme but we had one of those.
Didn't they say he was the weakest of the Four when they were originally locked away? C'thun had only just started to reawaken during the Second War of the Shifting Sands and Yogg-Saron had only just breached his prison when we went to Ulduar. We know N'Zoth was the figure behind Deathwing and the figure likely behind the Highborne turning into Naga. There's room for them to make him stronger than both C'thun and Yogg-Saron's characters in-game, simply due to circumstance. But yes, he is officially the weakest of the Old Gods who infested Azeroth.