There's something to unexpected or unintentional eloquence. You just know when someone says something for effect, and it's always more poignant when lyrics or words in a book hit you without your really expecting it, in a way that the writer probably didn't expect.
Here's some samples of what I mean from stuff I've read/ listened to lately.
From MGMT' 'It's working.”
Here, you focus
so I can see your faces
the eyes are wrong
how will I know if it's working right?
the tiny isles of bruises
the mangled lines
I love MGMT, and there is a certain ethereal quality to the writing of this particular song, and a real sense of measure that, even though the lyrics to the song are great, shows a certain restraint.
And even when it is calculated for effect, it's excusable when it doesn't stand alone, and is used to tie into something larger, like this from Milan Kundera in “The Book of Laughter and Forgetting:
It is 1971, and Mirek says that the struggle of man against power is the struggle of memory against forgetting.
That is his attempt to justify what his friends call carelessness: keeping a careful diary, preserving all correspondence, taking notes at meetings where there is discussion of the current situation and debate of where to go from there.
I think the point is that good writing is not just good writing for its own sake. There is a certain economy at work here, where you're not just saying things that sound pretty, but that have a use in the larger piece of writing. Which makes the phrase and sentence, not just well thought-out, but also a piece of the fabric. It's the difference, I think, between words as a way to bind ideas, and not to distract from the larger piece of writing, like a lead singer on a stage.