Hefner indeed had a huge impact on society, revolutionizing our sexual mores and tastes, and introducing young men to jazz, stylish clothes, travel, and literature, at a minimum. I purchased Playboy magazine in the mid-sixties, and immediately discovered Ian Fleming's James Bond novels being published in serial form in the magazine. Cartoons and jokes were also a cut above. And the women, ah the women! Beautiful, well-stacked babes, all expertly photographed for us to enjoy.
Back in the early 50's, US society was heavily sexually repressed, likely as a legacy of our Puritan founders and massive religiosity strictly imposed everywhere and all the time, a church on every corner, it seemed.
Hugh Hefner was instrumental in breaking that repression, and definitely one of the most influential men of the 20th century.