If it was just about a child having a doll respond to them then we'd have no problems. The issues are
a) The child's voice (and background sounds) are sent over the internet to the manufacturer and will very likely be available to three-letter-agencies and to creepy employees.
b) Paid promotions are likely. "Here Mattel, have $100,000 if your doll suggests having McNuggets twice a day"
c) Security is likely to be lousy and hacks will follow. "Barbie thinks Mommy is a dirty slut". "Mommy
Maybe we're all cynical, but we've been conditioned to be that way by repeated disappointment.