I’m also not convinced anyone beyond obsessed fans will book a trip for a new fireworks show anyway. Rather, strong fireworks are expected at WDW and they realized repeat bookings would decrease if they didn’t offer compelling nighttime spectaculars. They didn’t exactly market HEA beyond fan groups but they know guest ratings were lower for DE and that would not sustain return trips for 10 years or more. WDW guests have been trained to expect new rides at a healthy clip but not new fireworks shows.
Nighttime spectaculars mostly give guests a reason to stay in a park late and spend money on dinner, dessert, and $30 light-up bubble wands. This is obviously better for Disney than us going to bed at 7 pm out of boredom. I would also imagine, psychologically, an outstanding experience at the end of the day makes us more likely to overlook any daytime issues and say, “today was amazing and we should do this again.”