So I don't like prose poetry.
Not that a "prose poem" can't be an example of good writing--take today's Nepotist post--but it's not poetry.
Poetry is about restraint.
By definition it's artificial--all of our great accomplishments are. That's what civilization is, imposing artificial (and beneficial) restrictions on nature.
Prose, on the other hand, attempts to capture "natural" language--it's an uncivilizing force. This doesn't mean prose can't be beautiful. What it does mean is that when prose can be confused for poetry there's something amiss.
As the good Don says: civilization always consists in dressing oneself, not undressing.
Prose is language without clothes.
Poetry is language dressed to the nines.