When you launch minicom from the gnome-panel (programs>internet>minicom) it launches, but merely flashes a terminal window. Attempting to launch minicom from the command line results, of course, in the error: minicom: there is no global configuration file /etc/minirc.dfl Ask your sysadm to create one (with minicom -s). A configuration similar to rp3-config would probably be appropriate (asking for root's password to run the configuration), or simply adding a default global configuration file.
That indeed is a slight inconvenience. It isn't a bug though. I've changed the severity to "Enhancement" as that fits better. I won't guarantee anything, but it is a possible future enhancement.