The Star Trek musicians need to understand that they are licensing their music to a niche market, not a mass one such as with Star Wars.
Seriously? If Trek is so "niche," then why is the TrekBBS with only a single
Star Wars subforum, not the WarsBBS with a single
Star Trek subforum?
Wars would never have existed if
Trek hadn't paved the way by being a huge phenomenon, allowing Lucas to convince studios that a space opera movie could be profitable.
Star Trek pioneered sci-fi fandom as we know it -- conventions, fanzines, fanfiction, multi-series franchises, etc. The SW Expanded Universe came into being because Lucas saw how successful
Star Trek tie-in novels were and wanted in on that action. And even with all the expansion of the SW franchise under Disney, it still hasn't surpassed ST in the total number of movies and television episodes it's produced, and lags far behind it in the total number of tie-in novels, though it might surpass it in comics. Granted, SW is probably more profitable overall, but that doesn't mean it makes sense to call Trek "niche." That's like calling Saturn a dwarf planet because it's not quite as big as Jupiter.
Star Trek is easily the hugest American sci-fi franchise besides
Star Wars and the MCU, and
Star Wars only got huge by standing on
Star Trek's shoulders.
Anyway, looking into it, it looks to me as if most music licensing in the US is handled by
BMI, a performance rights organization. Composers use a variety of different music publishers (which I guess are sort of the equivalent of agents for writers or actors, responsible for arranging contracts and payments), but whenever I see a music publisher credited, it's always with "(BMI)" after the name, so I guess it's a larger entity that they're all members of. Although I think sometimes ASCAP handles them instead. But my soundtrack albums list BMI publishers for both Williams and the Trek composers. So I don't think there's any major difference in how their respective music is licensed.
Besides, who says
Star Trek isn't using legacy music in its shows? If anything, they've been using it a lot more in recent years. Almost everybody quotes the Courage fanfare, and Giacchino's Kelvin movie scores used the entire Courage theme as their end titles. The
Strange New Worlds theme is a partial quote and overall paraphrase of the Courage theme, and SNW episode scores have occasionally quoted other Trek music, such as Gerald Fried's "Amok Time" battle music.
Picard's main title theme is derived from one of Jay Chattaway's flute pieces from "The Inner Light."
Lower Decks quotes familiar musical themes, such as the
First Contact theme when the show visited Bozeman and the
Phoenix, and the DS9 theme when they went to the station.