I don't know if it was only a part. The world has moved on from the day, so a lot of what would have been in-your-face bleeding-edge progressivism back then no longer is.

The women could wear miniskirts. No-one was smoking. Uhura (African American) was not a maid or cook, but a well-respected competent peer, along with Chekhov (Soviet Russian), Sulu (Japanese), and McCoy (Caucasian American).

We may not think much of it now, and in the miniskirt case, think poorly of it, but back in the day, they were bleeding-edge social stances.