You state, "While this change could create issues with shipping CUPS with GNU/Linux, it is still available in most distributions." but never explain why that might be. There is a TON of software utilizing that license in every major Linux distribution, starting with the Apache webserver. Why would you believe that shipping CUPS with that license create issues for the distros?
telnet server should be disabled by default these days on all *nix boxes. ssh is a far better choice. You can actually do a lot more with it than you can with telnet, anyhow.
That said, though, there is one thing that a telnet client can be useful for that ssh can't do. It's handy for passing handcrafted commands to other services to see how they respond. However, the number of debugging options is so broad these days that hardly anybody bothers to use telnet for this purpose.
rsync is also really handy for grabbing all kinds of files for offline analysis. It should be in every sysadmin's troubleshooting toolkit.
Speaking of which, diff is really handy for comparing config files against baseline files to look for changes.
You state, "While this change could create issues with shipping CUPS with GNU/Linux, it is still available in most distributions." but never explain why that might be. There is a TON of software utilizing that license in every major Linux distribution, starting with the Apache webserver. Why would you believe that shipping CUPS with that license create issues for the distros?