This happened pretty much as soon as any new exotic weapon required a long tedious quest to get. This satisfied the players who wanted a route to getting the new exotic weapon, but killed the chances of a new exotic drop being a weapon or being exciting. I miss that excitement, Even when it was a disappointment. Made the grind a bit more interesting.

That's because all new exotic weapons are tied to paid content because of the free to play model I remember farming draksis for exotic engrams, desperately trying to get the Jade Rabbit, only for Rahool the Fool to give me another ducking last word Why I still haven't forgiven him, and think he should be tarred and feathered and threw off the highest point of the Tower, then find out where he landed and tbag his corpse

Exotic engrams dropping like crazy probably has something to do with the build freaks that like focusing for build stat distribution.