Fedora

Warren wondered whether it would make any sense including a version of scp or ssh which do not encrypt their traffic on the network.

As far as I can see, such a tool would indeed be useful for many tasks. "brokensh" might not be that useful, but "brokencp" is certainly useful.
Consider the roadwarrior with his notebook who is transferring some data from the server to his notebook. He is already encrypting the data-traffic by using openvpn or ipsec. The network between his tunnel-terminator and the server can be considered secure. He would save CPU-time by not having to encrypt the traffic twice.
Or the system-administrator who has to copy a whole tree of files, including permissions from one machine to another. He could just call tar c /dir | ssh root@server tar xv to achieve this. If the machines are directly connected the transfer is probably faster, as the data does not need to be encrypted. Generally, I do help myself in this case by using netcat, but still.

I for one do like the idea of selectivly disabling encryption for scp as long as the authentication against the remote system is secure, that is no cleartext password crosses the wire. I do not care if the attacker sniffing my line is able to reconstruct the latest Fedora ISO image which I'm copying, I do care that he is not able to sniff my password.