The fact that the dolls have a gender allows children to make an important difference between them, strengthening knowledge of differential facts. They do not contain batteries or make any sound, so the dolls do what the child wants them to. This differentiates them from other dolls that subject the child to a specific play pattern. The variation in available models means that there is always a particular model for a specific need.
The dolls are hermetically sealed for 0-3 play so can't be bathed.