I'd further elaborate on your answer with:
Even if you can only monitor things, instead of directly issuing commands, it's still information you're leaking.
Information leaks are still a class of vulnerability for a reason. It can give an attacker information on your network topology that he wouldn't usually have.
The less attack surface exposed, the better. Generally, if something is exposed to the Internet that has no (good) reason to be, it's a vulnerability.