I still have a few of these books. Basically, their only intent was to teach young (very young) viewers day-to-day life lessons. From what I can remember, there really wasn't much of an attempt to develop characters. In fact, in these books the Muppets were more like scenery (in fact, Animal, Bunsen, and Beaker literally were scenery in these books).
I have always wondered how a "Muppet Kids" series would have fared if it was more along the lines of a Little Rascals/Our Gang series.