It's a ludicrous expectation that the sequel won' have less to do than it's predecessor?
Destiny 2 has way more to do than its predecessor. More patrols, missions, caves, new adventures, more story missions, powers, vendors, larger game worlds etc.
A key difference is D2 isn't nearly as stingy with its loot, and isn't nearly as grindy either. Ultimately in D2, unlike D1, there's less reason to repeat the same stuff over and over, which in my opinion is a good thing which better respects my time.