Adding unpredictability to a trivia format
A lot of trivia formats let teams pick their own category every round, which tends to favor whoever's strongest in a narrow set of topics. Randomizing the category with a spin levels that out and adds a bit of suspense before each round even starts.
The same wheel works for other trivia-adjacent randomization too — deciding which team answers first, assigning random point multipliers, or picking a wildcard bonus round category.