The problem turned out to be the usage of the line connection: ansible.netcommon.network_cli in the playbook. It seems that by having that line, Ansible requires you to specify the ansible_network_os variable.

I've removed the line, set hosts: to all and cleared the /etc/ansible/hosts file and was able to run the playbook remotely as follows ansible-playbook -i 192.168.1.184, setup-raspberrypi.yml --ask-pass.