Didn't most of the Fallen cast get sick at one point?
I applaud A&D for taking bold risks, but that house very clearly blew up in their faces.
From what I saw, it wasn't even all that "bold." They've had flyers before. It's almost become a go-to "look at what we can do" because so few haunts in the world have the infrastructure to support them.
Universal, at the end of the day, is just really inconsistent in how they "chart" out scares. It can't all be startle scares but, because it's a conga line, the only "scenes" that work are ones where the scareactors remain visible (a doctor working on a patient, someone sitting at a desk, etc). With the way Universal cast the roles, however, there's a high risk of poor performers falling into those "featured" positions when they'd be better suited to an assembly line scare (press the button, appear, disappear, repeat). The more of those "open" scares a house has, the greater the likelihood you'll end up with bad performers in important spots.
HotY means little. It's the people who made the houses determining which house they like the most. It's essentially determined after week 2. Location means little. All the spaces are now climate controlled and budgets are much better dispersed. Universal's focus is making houses pretty and with a high throughput. They make houses "scarier" by making them louder.
The most important thing to determining the success of any haunt is the performers. A good cast can make a garbage house incredible (Havoc). A mediocre cast can send an expected favorite tumbling (Hades). Unfortunately, it boils down to luck since Universal doesn't base any scareactor assignments on talent.