Sentences with line breaks

You hear/see that phrase get tossed around quite a bit, and it's generally code for "poorly-written narrative poetry." There's a general backlash against narrative in the current analogue to an avant-garde (I won't call it an actual avant-garde, as I suspect our postmodernity prevents a typical AG from occurring - the most AG productions these days would actually be reactionary ones). If there is to be narrative, it should be distrusting of itself and its own language. It should cancel itself out, suggest alternates to itself, or otherwise undermine the reader's attempt to make it linear/straight (puns intended).

I'm actually very much in favor of this approach, to a certain extent. Even as diluvium, for example, will unroll a narrative tale, all the seeds of that tale's dissolution are contained in the same pages (e.g. the second page has Noah and his wife thanking God for their new lives in language that evokes birth, while surrounding them are, among other lines, bits of Apollinaire's "Il pleut" that begins "it's raining women's voices as though they were dead even in memory").

What I don't like about the phrase "sentences with line breaks" however is the tacit assumption that if it is a sentence, it will be sensible/narrative/prosaic. I link you here to an excerpt from James Longenbach's The Art of the Poetic Line in which he tackles a series of lines/sentences from King Lear. Lear's madness is expressed through a series of sentences which, while remaining syntactically normal (i.e. the grammar all works), bounce crazily from subject to subject, tone to tone. By jamming the abnormal into a recognized framework, Shakespeare makes Lear's insanity even more disturbing, more postmodern, as it were, than if Lear were simply babbling syllables the entire time.

Longenbach's example is hundreds of years old, but let's not pretend that conceits we consider postmodern don't appear well before the 20th century (Beowulf and The Frogs, I'm looking at you).

I'm as annoyed as anyone (maybe even more so) when a so-called poem is just sentence after sentence with no real reason - there is no rhetorical building, no musicality, no jumbling of disparate subjects. But can we stop with the automatic dismissal of the sentence?