All content is locked behind story because it's a story-driven game. You might not like it or agree with it, but the entire game is made that way from start to finish and it doesn't seem likely that could ever change. Even the most forgettable and irrelevant side dungeons have a story associated with them if you watch the cutscenes.

But you require the raids because its story is directly related to it and necessary for the story in Bozja.