Got hawkmoon one Sunday morning a few weeks ago. I was a pre-order customer that's always run roc strikes and I've never gotten an exotic. I still think to this day there is a trigger to how you can get a legendary engram or a higher chance for an exotic (higher in the context of the chance the other two players have). I did level up my vanguard after a roc strike and got 3 legendary engrams that gave me 2 exotics but that's only happened once between 3 players and multiple vanguard levels. Oh and speaking of the method to get higher rewards, I also think a lot of the higher level players know the secret but don't share cause every time I get into a roc strike with 32s they are taking the exact same approach and the chances of it being a coincidence are way too low.