Choirs may “age out”—the older members simply can’t (or don’t want to) climb the steps anymore, and the younger people who would replace them want to worship with their families rather than spend half the service on a platform or in a loft, especially in churches where there is no children’s church or age-segregated worship. Sometimes members come to prefer singing with their congregational neighbors rather than being more or less sung at by an amplified, center-stage team.
Choirs (and their casual, modern descendants worship teams and praise bands) have been near-ubiquitous in Reformed churches for less than two centuries, but just like government programs, once instituted these groups are difficult to disband even though their historical pedigree is weak. Arrangements may be changed (from choir to praise team), expanded, or downsized, but any pastor or session/consistory knows that messing with the music is akin to playing with fire.
The music-loving Welsh even had a term (cythraul canu) for problems and strife caused by music and choirs. Dr. Martyn Lloyd-Jones sometimes referred to it in English: the devil in the singing. Many pastors and church officers have understood the concept all too well, resisting change and preferring the known “devil” to the unknown one.
But change does happen. Diminution or even elimination of church “music programs” is not completely unknown.