It's amazing that they got so much right with the HM especially when they first built the exterior at Disneyland in '63, the only thing that had been settled on was the stretching room pre-show, it was still to be a walkthrough at the time.
It probably wasn't intentional, but the Haunted Mansion feels like there's secret after secret to discover and lore to uncover. No one cares about the name or histories of the Auctioneer or any of the trio in jail in Pirates, but everyone wants to know if the Ghost Host was Master Gracey or what was up with the Hatbox Ghost.