What you're not understanding is that having a special expert medal would cause all the expert servers to be filled with inexperienced players vying for that medal, frustrating veteran players with incompetence such as snipers that can't drop uber medics, heavies that dumps crit canteens onto tanks, and pyros that run to heal-on-hit/kill bots and heal their full health back. It will be impossible to play an expert mission without friends because all the servers will be overrun with noobs, to put it another way.
This is already a widely-complained problem with Voltaic Violence, even though it doesn't have an expert medal. A special expert medal would only exacerbate these issues (and perhaps many more), so until we come up with solutions to these problems, we do not plan on implementing an expert-only medal.
There are preliminary talks on prohibiting players from joining expert servers unless they have completed a few advanced missions, but the Moonlight staff has not formally legislated anything yet.
This is already a widely-complained problem with Voltaic Violence, even though it doesn't have an expert medal. A special expert medal would only exacerbate these issues (and perhaps many more), so until we come up with solutions to these problems, we do not plan on implementing an expert-only medal.
There are preliminary talks on prohibiting players from joining expert servers unless they have completed a few advanced missions, but the Moonlight staff has not formally legislated anything yet.