Very true. The early Church forbid instrumental music for many reasons, the main one was that most of those songs and people who played the instruments did so in pagan worship. Since the early Church was really bucking the culture of the time, they didn't want people to hear the water organ and think it was just another temple to Athena or something.
Of interest, many Eastern Orthodox still don't have incitements.
I think now it's about aural cues. IF you associate certain music and sounds with church and worship, it's just another way to shift yourself into a spiritual state. The whole package of incense, lighting and pipe organs happened not by mistake, but as a way of creating a higher mindset.
That's why a chick with a microphone and drummer behind her makes me think 'night club' and no matter how many 'praise Gods' are in the lyrics, I still am in 'nightclub' mode. Not a happy one at that.
I hate chicks with mics ;)