The old school linear approach would be ideal for this game. I feel like the hub area was a last minute decision because I'm seeing all sorts of little remnants of that idea all over the older maps like the mall in the theatre area having more complex puzzles yet it's barely mid game and then it goes back to easy puzzles again. The dialog comes up at really inconsistent times like it's totally silent in the area after the first locker room with nothing in the hub, nothing in the theatre and nothingin the conference room but then in the family resort he starts talking again.
My over all recommendation is similar to what people above me have stated. Make it linear again with the hub world being a level with more darkness to it. Maybe make some of the lights flicker and go out for dramatic effect. One thing I wish for exploring mode in a linear version of this game would be the ability to go back through doors you just came from and go backwards too.
If the hub world is to stay maybe make it go through changes as you go through levels like maybe make lights start going out and the shadow guy show up a bit in the hub in later game and then make his presence a real threat in the last level.