If you have network ports that are not in use on your network, you should disable them. While it makes it easy for anyone to connect, it also makes it easy for anyone from the outside to gain access also. It is much easier to walk into an office and plug in and gain access than to hack a firewall. Most remote offices are not monitored very well and provide an easy target for hackers.
If that is a problem you can also invest in a solution called network access control or NAC.