I think that part of the appeal is in the heart of the creator. He was an autistic man who wanted to tell a story of developing friendships through the unconditional love of pets. I think many children are attracted to the pet ownership aspect and communicate through their knowledge of the creatures.
My own niece, at 10, who is mildly autistic never willingly spoke to another child, especially a stranger. However, through Pokemon Go! She had her first ever initiated social interaction because of that game…and because the other kids knew and were willing to discuss all 600 zillion little pets.
