Time travel always complicates storytelling. When they started ShB, they werent sure exactly how they were ending it. As such, they could get away with the recommended but not required bit. If you hadnt done the raids, then the Exarch says that its something you would do in the future. You doing the raids at some point is required for him to exist, but him being from the future means it didnt matter when you did them. Then he ended up being a super popular character, and they decided to add him to the scions team going forward. The end of 5.3 sees you reopening the sealed tower, and reawakening G'raha. You cant reopen a tower that you never opened/sealed in the first place, nor can you awaken someone who hasnt gone to sleep. And while the workaround of 2 dialogue options for certain scenes worked ok for 5.0, you cant write a whole expansion with 2 versions of every scene that include and exclude a major character.