They used to call picture books with more text on the page--storybooks. However, there's very little interest in longer picture books these days. Pbs and storybooks are both intended to be read to the child by an adult. These days pbs are concise with only one or two sentences on each page because...
1. Parents often read picture books to children at night. An exhausted parent wants a book that is concise and can be read quickly, if necessary.
2. Children's attention spans are shorter than they used to be.
3. Children six and above often are starting to read beginning readers and chapter books, which they peruse by themselves. So picture books are mostly for younger children.
Agents report having little success in selling longer picture books in the last few years.
Of course these are generalizations that don't apply to any specific child or book--there ARE exceptions, but not many. In addition, nonfiction picture books can be more text-heavy, as these are often read by older children for book reports, etc.