Shouldn't be surprised
Musk has a penchant for overhyping features like autopilot and now full self drive. Then it gets delivered in some underwhelming, not-fit-for-purpose form and the stock tanks. Even worse, sometimes people get themselves killed through its inadequacies.
He'd be better off to understate what it can do and only deliver what is achievable. Anyone thinking "full self drive" will produce a car fully capable of driving itself without driver intervention is kidding themselves.