Back in the mid-60s/early 70s, my MIL used to make those types of books all the time... and not just for her grandkids, but for her students when she worked with mentally challenged kids. These books actually helped the kids a lot (upper grade school kids who were actually functioning at a 2–6-year old levels). The kids idolized my MIL and she felt the same way about them. Unfortunately the school closed, so my MIL went on to work with special ed kids in public elementary schools.
If there aren't any patterns for these types of books available "out there" I strongly encourage you to go ahead and make your patterns. I believe they'd be well worth the time and greatly appreciated.