It's not that they force Kubernetes to be more complex, it's that they muddy the waters. I clearly understand that they're optional, and that they're an add-on essentially, but it might not look this way to a newcomer.

People are being encouraged to download a helm chart before they even write their first kubernetes resource definition. People might start using this Operator Framework before they implement their own operator from scratch (that's kind of the point) -- though honestly it's unlikely that they'll actually be clueless since it's for cluster operators.