1. There's utility in information compression. Extraversion encompasses a lot more than "talking to people"; it encompasses things like positivity, social proac

1. There's utility in information compression. Extraversion encompasses a lot more than "talking to people"; it encompasses things like positivity, social proactivity, energy level etc. If you say "someone is more extraverted than 99% of the population" you can make a lot of inferences other than "likes to talk to people". The Big Five aren't everything, but they convey a lot. 2. There are theories underlying the Big Five; the Big Five and its variants are so well-replicated and appear in so many settings that they have become something to be explained, which is generative. E.g., there's a theory that extraversion basically refers to basal level of active, positive emotion, neuroticism refers to basal level of negative emotion; agreeableness to empathic ability processes etc. Maybe these are or aren't right, but there are non trivial theories about them that are very elaborated. You just don't hear about them as much necessarily because you don't hear about the Big Five as much, and because there are multiple theories for the Big Five -- as opposed to the Myers Brigs, which is tied to one account.