"I think you'll find that in religious observance, the voice, using singing to carry the words, is sometimes seen as a pure expression of the soul, whereas instrumental music and accompaniment can be seen as a dangerous distraction from worship."

I'm not sure it's always a high-'low' sort of thing. Compare the singing of Primitive Baptists to the music performed in Holiness and Pentecostal churches. The former eschew musical instruments, while the later use guitars and extensive rhythmic accompaniment including hand-clapping, etc. Neither would be considered 'high' church. Both are sincere expressions of faith and are valid in context.