I saw South Pacific when it came out in 1958. I remember the impact this scene had on me. I felt the truth in the lyrics. Especially since the character supposedly singing them (sounds like someone else's voice) has fallen in love with a woman with "brown" skin, against the law still in many states, at least if you wanted to marry.
I was sixteen and just starting to notice, and secretly falling in love with, some of my fellow teens who happened to be females with darker skin than mine. It's great that inter-racial love (and marriage) is no longer against the law and even quite acceptable most places in this country now. But obviously after this weekend, there are people still being carefully taught.