Other models actually did settle for higher numbers of factors, but higher numbers were usually found to have categories that could be reasonably collapsed into

Other models actually did settle for higher numbers of factors, but higher numbers were usually found to have categories that could be reasonably collapsed into one of the Big 5. Fwiw, my understanding is that most psychologists believe that with further study, these categories will map to actual functioning of the brain and nerve systems. For example, "Neuroticism" will somehow map to the excitability of certain nerve systems and "Agreeableness" will somehow map to functioning of our mirror and mentalizing systems. "Conscientiousness" will map to inhibiting functions, "Openness" will map to approach/flee type emotional functions, and "Extraversion" will map to systems like dopamine release on securing rewards for behavior.