I don't mean to put down these suggestions; I think that they're interesting and helpful. But here is a cautionary note for pre-published writers about to push away from wonderful work that doesn't meet the criteria:
All but one of my PB's violate 4 or 5 of these criteria, depending on how you interpret the bit about refrains, how prominent the repetition has to be. The books in question are with four different publishers, ranging from big 5 (or is it now down to 4?) to tiny. Two of them aren't out yet, so some are quite recent sales.
It would be very sad if writers who are drawn to folklore decided that working in the genre was a waste of time when, in fact, retold and fractured tales are alive and well and selling (although certainly not as well as Olivia or Fancy Nancy, there's still room for them). Or if stories that demand more words ended up stuffed in bankers boxes. Or if stories with religious subtext and messages -- assuming no hit over the head with a hammer engraved with the words "and the moral of this story is" messages -- never got sent to secular publishers.
Over the years I've heard no anthropomorphic talking animals (my first book), no retold folktales (four books), no books with only adult characters (all the folktales and one non-folktale), no rhyme (I don't do these, but how many terrific rhyming books have you seen recently?), and all sorts of other prohibitions that are routinely violated by lots and lots of writers.
OK, probably a humorless 4,000 word PB in which a talking refrigerator overcomes its fear of the leafy green vegetables lurking in its produce drawer thanks to divine intervention, written in mind-numbing iambic pentameter, is not going to jump out of the slush pile any time soon, but I think that if you read a lot of PB's and exercise reasonable judgment, you have a lot of room to be creative and follow your passion with an awareness but not a slavish dedication to producing what's supposed to be hot.