I think you got to look at the data first before you make this argument. If you are going to say video games don't lend themselves to theme parks than you should hate the Nintendo deal.
Video game industry not even including consoles makes more than the movie industry.
Why Aren't Video Games as Respected as Movies? | Hollywood Reporter
Investing in Video Games: This Industry Pulls In More Revenue Than Movies, Music - Nasdaq.com
Secondly, even when using game data, while Nintendo characters are extremely recognized, sales data shows that other IPs are just as valuable if not more.
I do find it interesting Final Fantasy is niche yet the series has outsold Zelda, Mario Kart, and Donkey Kong in pure sales.
Thirdly, Universal is building an attraction based off Jason Bourne. The term niche has gone out the window since they are making a ride that didn't even break 500 mil at the box office including the international numbers. Also some of Disney's greatest attractions where based on little known ips (Mr Toad's Wild Ride, Splash Mountain, etc).
Lastly, its not the IP, its the execution.
Maybe living in Asia where people from ages 10-60 go to PC cafes to game and pay arcade games like crazy have blinded me from life in the states but last time I checked these parks were trying to be world class not just for the domestic guests.