An API Key in the URL over SSL is hardly "unrestricted".
I'm pretty sure that:
//192.168.1.100/rest/nodes/12345/key/772ac1a55fab1122f3b369ee9cd31549/cmd/dof
is much more secure than:
//admin:admin@192.168.1.100/rest/nodes/12345/cmd/dof
My first guess on any basic authentication mechanism is going to be "admin:admin". It's going to take a while before you guess my api key. Even unencrypted, the api key still gives me a fighting chance over basic authentication.
With multiple API Keys, I can revoke certain devices. Rather than having to change my password on my other n-1 devices because a password leaked.
Respectfully.