There is a difference between short stories that require minimal build up and contextual relevance, and a screenplay that juggles both in-universe relevance and moments that promote player agency. Not to mention that the entire writing department is almost 100% working together, it's just that there is more freedom when it comes to writing short story style narratives that don't need to mesh perfectly with the existing narrative so long as they just take context of in-universe expectations into consideration. Edit: Also, a lot of the people who were the writers during Taken King and Rise of Iron are still the writers for Forsaken. Heck, Michael Zenke the narrative lead was a senior writer during Taken King. I think they're okay. (This actually makes a lot of sense considering the context of the Dreaming City and Oryx.)