If you're going to make that argument, you have to show that the older IPs you're nostalgic about are, in some objective way, more popular than F&F. And I don't think you can do that.
Top 10 Universal Franchises inflation adjusted box office take per film:
1 - Jurassic Park, 7 films, $588.3M per
2 - Jaws, 4 films, $542.1M per
3 - Back to the Future, 3 films, $407.3M per
4 - Secret Life of Pets, 2 films, $339.3M per
5 - Bourne, 5 films, $260.8M per
6 - Despicable Me, 10 films, $241.6M per
7 - Shrek, 11 films, $237.8M per
8 - Fast and the Furious 12 films, $218.7M per
9 - Mummy, 5 films, $218.7M per
10 - Minions, 6 films, $201.6M per
And then for each of these here's the critics weighted score (at release) and audience weighted score (currently) according to Rotten Tomatoes (meaning the most popular box office movies count more than lowest):
1 - Jurassic Park, Critics 67%, Audience 78%
2 - Jaws, Critics 74%, Audience 76%
3 - Back to the Future, Critics 86%, Audience 89%
4 - Secret Life of Pets, Critics 58%, Audience 63%
5 - Bourne, Critics 73%, Audience 81%
6 - Despicable Me, Critics 63%, Audience 83%
7 - Shrek, Critics 67%, Audience 70%
8 - Fast and the Furious, Critics 56%, Audience 78%
9 - Mummy, Critics 50%, Audience 62%
10 - Minions, Critics 54%, Audience 75%
So composite weighting all of that (35% of overall ranking from each category) and Universals Top 10 most popular franchises based on per film performance is: (surprisingly reviews pulled some from the top 15 into the top 10, so I'll give all 15 I had)
1 - Back to the Future
2 - Jurassic Park
3 - How to Train your Dragon
4 - Jaws
5 - King Fu Panda
6 - Bourne
7 - Despicable Me
8 - Shrek
9 - Fast and Fruious
10 - Secret Life of Pets
11 - Pitch Perfect
12 - Meet the Parents
13 - Minions
14 - The Mummy
15 - Halloween
So what isn't represented in parks?
Jaws is only at Japan, Halloween is a HHN house so they have minimal representation despite its popularity. Nothing at all: Back to the Future, Meet the Parents, Bourne, Pitch Perfect, and Halloween
Remove what doesn't lend itself to a ride and Universal's most popular attractions without US based park representation are in order:
Back to the future, Jaws, Bourne
Now you can debate Shrek and Kung Fu Panda with the minimal play zone areas (a jungle gym and a splash zone).