Bi-racial unions were pretty controversial in the 60's.
Interestingly, no one had a problem with Kirk kissing Elaan, portrayed by France Nuyen....an Asian-American woman.
Hence, by-passing that aforementioned kiss and focusing on the Kirk/Uhura kiss, claiming it was television's first interracial kiss....
Bullshi...
She is actually bi-racial and of French extraction -- many "Asian" actors in Hollywood are of mixed race. We have to remember that politics drives a lot of what gets discussed as "cultural" issues, and race in the United States has almost always been defined as a black/white issue.
Even if there was a high degree of anger or praise for the scene with Kirk and Elaan, it would easily be overshadowed.