It's not just
about being flawed. It's about being flesh-and-blood human beings, with vices and virtues, strengths and weaknesses, conflicting emotions and priorities, moments of determination and moments of doubt.
That was the great thing about Kirk. He wasn't just a perfect paragon of virtue. He lost his temper sometimes, could be plagued by guilt or doubt, but he could also be cool under pressure and maintain a sense of humor most of the time. He was a complete character who sweated and bled and made mistakes sometimes, but always came through the end.