The hallways ae mainly before the AT-AT room... it helps with the grand reveal (Cinematically speaking its like going from a close-up to a wide angle view). After that there's more than just hallways - you have blasts, encounter with Kylo, elevator with lightsaber, battle with the cannons, the last encounter with Kylo, and then the drop and escape. The beginning is mostly tunnels because a this point, the chase hasn't begun.

<its similar to how Pirates closes in right before the scene with the pirate ship bombarding the city. Its designed to be a grand reveal>