The kiss that caused a stir.
In the 1960s, when many still frowned upon mixed-race couples, Star Trek came stomping in and gave a glimmer of hope for future relationships when they aired a white man and an African-American woman kissing. Thus it became a revolutionary show.
Of course, this hand gesture means "read between the lines"...
He came up with it for the character. He's the reason it's in the show. That's all that anyone needs to know. Pointy ears weren't a new thing, either.