If you buy cake mix and the ingredients does that entitle you to a cake? Not if you burn it or screw up the recipe. Destiny DLC acts the same way. It promised to add content to the game (which it did) but you still need to unlock it. Just like you had to complete the story to gain access to the PoE or wait for RNG/Xur to get a new exotic, you also need to get flawless to get to the Lighthouse. PS: You keep it for the weekend and there is nothing there other than the chest. I went there once to get my rewards and once more to record a tour of it. It kinda sucks ( - _ - ).