You say "a very clever and elaborate (read, "expensive") LCD technology. " but if anything, the Dolby system is by far the most clever (to me).  Using separate portions of the visible light spectrum has many interesting applications (for example, you could use a very narrow band projector and glasses and allow for watching films in daylight!)  Toggling LCDs on the other hand are fairly brute force and old tech.

(frequency multiplexing also allows for plain white screens)