The modern consensus is that it should ask you what class of network you're connected to and configure it accordingly, as more permissive rules are better for h

The modern consensus is that it should ask you what class of network you're connected to and configure it accordingly, as more permissive rules are better for home networks and the opposite for public networks. But also, if Ubuntu didn't run network services by default, there would be no need to secure them with iptables. So defaults affect defaults.