Like a song, a picture book is meant to be heard. Still, although a reader may happen to know the featured song, it’s only fair to expect the book to succeed, its text to flow, for someone who doesn’t. I’m familiar with Dylan’s glorious “If Not for You,” so I know to add a beat to “nowhere” in the line “Without your love I’d be nowhere at all” when I’m reading it on paper; otherwise I might be at sea, rhythm-wise, with the corresponding page’s parent-child doggy sailing duo.While a song’s repetitive elements may seem suited to picture books, they can also present problems. Some lyrics are pure poetry, but a poem seldom has a chorus — the thing that listeners eagerly anticipate but that, should it become tic-like, readers may wish they could fast-forward over. The adorable, near-pocket-size “What the World Needs Now Is Love,” last holiday season’s repackaging of the Burt Bacharach and Hal David charmer, with exuberant art by Mary Kate McDevitt, uses the line “What the world needs now is love, sweet love” seven times in 24 pages of text. That’s too much love, babe.