I was just comparing Kirk and Picard in another thread when I realized that Kirk's actions as Captain needs to be seen in light of the era TOS was filmed. It was the 1960s and it was the decade of when youth began confronting authority and I think that had a great influence on the scripts and how Kirk played his role as Captain.
I'm not sure the zeitgeist
had that much to do with it. Youth has been rebelling against authority since before the time of Socrates.
True, I remember reading that the 60s was the first time when the rebelling youth became an economic power in its own right and that contributed to a focusing on them within the context of the larger culture.