Blame the FCC for this one.
The FCC, around the early 90's (after Pee-Wee's Playhouse got cancelled), began to become concerned that Children's programming wasn't educational enough, and enstated the Children's Television Act, a set of rules to improve the state of Children's programming being aired.
The famous Chicago child's program, Bozo's Circus, also talked about children's books, making it a segment on the show around 1996 when the FCC didn't think the act that was passed in 1990 was being taken seriously enough and decided to make the guidelines mandatory.
These days, about half the Saturday and Sunday broadcasting of children's programs is of educational or informative (E/I) origin, usually airing between 7 to 10 in the morning, the core time period for E/I programming.
If Pee-Wee's Playhouse was still airing these days, there would be educational content somewhere in the show, because the FCC says there had to be, and the Broadway show was just reflecting that.