Captain Shatner wrote:
Out of curiosity, why was the score for Star Trek dropped after TOS ended? When I finally watched TMP, imagine my surprise when I heard the score commonly associated with The Next Generation! You don't even hear overtones of the old operatic theme song in the movie!
Yes, you do. Both of the times that Kirk's captain's log voiceover is heard in the movie, the musical accompaniment is the TOS theme, and they actually brought in Alexander Courage himself to arrange it for those cues. What you don't hear in TMP is the "fanfare" part, the first half of the TOS title music that plays under the "Space, the final frontier" narration. It's the only Trek movie that doesn't use that portion of the theme, but it does use the other portion.
(And the TOS theme was hardly "operatic." It was written in the style of popular songs of the day, basically a pastiche of "Beyond the Blue Horizon" with a bossa nova rhythm evoking "Begin the Beguine." It even had lyrics written by Roddenberry, but they weren't very good.)
The reason they used a different theme is because they hired Jerry Goldsmith to do the movie instead of Alexander Courage. In the same way, the animated series had a different theme because Ray Ellis did it instead of Courage (though it was a close pastiche of the Courage theme). It's not uncommon for movie sequels, revival TV series, animated adaptations, etc. to have different music than the original did. Sometimes a series will even change its own theme music sometime during its run (e.g. Lost in Space
, the 2000 Invisible Man
, or Andromeda
), either because they get a new composer or just want to convey something different.