Here's what editors tell writers when discussing picture books: "We want books with actual story arcs--we want a character who has a problem and who works to solve that problem. Also NO RHYMING!!!!"
And yet . . .
I spent all day yesterday and part of this morning reviewing new books for The King's English publication (THE INKSLINGER), and pretty much all of the books violated these rules. They rhymed. And many of them didn't have much of a story--just charming moments. So (as Phil Dunphy says) Why The Face?
I will say this. I do think picture books that have some sort of a storyline wear better than those that don't.