Captain Shatner wrote:
Although I think it has something to do with John Williams and the success of Star Wars IV.
Well, to some extent that's true. Of course, Jerry Goldsmith at the time was probably a bigger name in the industry than Williams, with a lot more film credits under his belt, though they'd been in the business for roughly the same length of time and had both begun in television. But according to the liner notes for the recently-released La-La Land Records Limited Edition TMP soundtrack box set, written by Jeff Bond and Mike Mattesino:
Essentially a modernist throughout the first half of his career, Goldsmith made a shift into romanticism with Star Trek. John Williams' success on Star Wars, emphasizing the familiarity rather than strangeness of outer space (postmodernism, rather than modernism), had changed the culture: "I think when I first started talking to Bob [Wise] about the music, he didn't say, 'I want something like Star Wars' or something in that idiom, but it was more or less that that was what was out there and that was very successful... it made sense. ..."
So something to do with it, yes, but indirectly. And it's not like Williams's influence was the reason they didn't use the Courage theme. They didn't use the Courage theme because they hired Goldsmith instead of Courage.
Also -- at the time, it wasn't "Star Wars IV." It was just Star Wars