Fans rescued the first show.
Star Trek was the first show to see the importance of fans. In 1968, when they planned to cancel the series after two seasons, some science fiction fans got wind of it and organized a mass mailing of letters to try to save it. Thanks to this, another season was made, followed by a movie, and the rest is history. To this day, productions of the plot are still being made.
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.