Tunes and instrumentation should help to convey the lyrics/narrative, surely?

I dispute this most vociferously. In Popular Musics, Folk, Classical idioms the world over the lyrics are often obscured by the music - much less the story. All that natters is the music, which carries a deeper narrative meaning that mere words can convey, otherwise, why bother singing them? Ballads likewise. I switch off from the immediate narrative and lose myself in the sound & images, which is where the real magic lies; after all, ballad narratives aren't exactly that riveting, unlike the episodic imagery & language which is.

How we each listen to songs is just as personal as how we sing them. When I was a kid, I had friends who bought lyric mags of Pop Songs to hear what was going on. I never cared. I used to think Big Yellow Taxi was about the Caud Lad o' Hyton (don't ask!) and even to this day listen to all manner of vocal musics from different eras, countries & traditions where the sound is all that matters. Words as written or spoken prose carry different levels of meaning to words in poems; words in song takes this even deeper. The surface narrative is superficial; the inner seance of thing is what it's about.

For me anyway.