I don’t mean to suggest that
DAS was the only (or perhaps primary) reason people’s satisfaction was decreasing (I personally am still dissatisfied with how few nights there are extended evening hours, which has nothing to do with DAS, along with most items you bulleted!) but I am certain that it was a significant factor or they wouldn’t be going through the hassle of changing it.
Many casual guests don’t care about merch quality and variety (in my opinion, it’s about the same as it ever was except that they really love the spirit jerseys which I do not like — saved us 100s over the past few years) or the food (I don’t see a decline there either), but they do care if the average wait time is 35m instead of 25m— 10m a ride aounds like a negligible amount in the abstract but it adds up and can be 2 (or more) extra hours over the course of a day, or put another way 3-5 rides. In addition, if there are zero (near zero) rides without at least a 15m wait, it makes the day more exhausting even for able bodied families. I’m less familiar with WDW, but at DLR, even the rides that were often walk ons (on weekdays in slow seasons) are increasingly likely to be 20-30m waits.