Hi, glad you had lovely time with your husband! For your question, Epic Universe practically doubled Universal's physical footprint in Orlando, bringing massive daily capacity requirements. There simply aren't enough teenagers and thrill seeking adults in the vacation pipeline to keep a park of that scale operating at profitable capacity year round. Expanding the demographic net downward to include toddlers and early elementary children opens up the single largest segment of the theme park market.
Also, young children drive retail. The under 10 demographic is a massive catalyst for high margin ancillary spending. character dining, interactive toys, costumes, and plush merchandise. The integration of interactive elements in Epic Universe (like the Power-Up Bands in Super Nintendo World) creates a continuous monetization loop that older, ride focused guests typically don't engage in at the same volume.
Hope my writing helped!