You're not wrong, but the anchor rides of those two expansions are huge advancements in themed rides and compelling weenies that feature far more relevant and compelling IPs. The immersion of Harry Potter, specifically, highlights a desire of the fans to BE wizards, and everything about those expansions allows them to do that.
Avatar features a boat ride and an inverted simulator that, while are likely going to be enjoyable, I doubt will set new standards or actually blow away expectations.