Film and video game music has a clear goal, to provoke emotional responses coherent with the message of the corresponding scene. Because there are so many films, most receiving their own scores, there is an 'inventory' of tricks, elements that film composers have at their disposal, established so in the cultural consciousness. Some are even on TvTropes (a site not normally about music), like Dramatic Timpani and Deathly Dies Irae. These shortcuts can establish a mood or a setting in just a few seconds.
Having been introduced to microtonal music recently, and the truly alien chord progressions you can produce by going outside the typical 12-tone temperament, I wondered: why isn't this used for every alien theme, all the time? The listeners are not used to it, but the same goes for compound meter, and 5/4 is used liberally for villain themes.
Microtonality has the issue that you cannot use standard brass, woodwinds, and regular tuned percussion; but strings, the human voice and electronic instruments are still fair game. Particularly the latter is going to be very appropriate for any aliens.
Yet, in this extensive list of pieces in 24-tone temperament (which is a microtonal scale quite easier to grasp than any of the other multipliers), there's only two movie scores; one from the 1960's, and one by Danny Elfman. Compared to the list of pieces in quintuple meter specifically, and the popular music section does not even try to be comprehensive.
So why is microtonality so rare in popular music, particularly soundtracks for films and video games, that deal with aliens or generally other-worldly beings, that would be so well served by exotic scales?