I'm not sure whether this is even possible or if things like these are already in the mission editor, but there's a lot of interesting situations you could create with a few of these.

•Mission limiters: certain missions may require or even force you to fly a specific ship, use a specific loadout, etc. Along similar lines, certain missions would restrict your abilities to do certain things, i.e. travel to certain sectors/stations/systems... perhaps even prevent you from talking with other players.

•Mission statistics: the ability to track certain statistics in a mission, such as accuracy (shots fired vs shots hit), % damage taken, % damage done as an individual vs group...

Even if not specific to missions it would be awesome to be able to track of accuracy (shots fired vs shots hit), % damage taken, % damage done as an individual vs group, with some sort of mission wrap-up/review at the end, or just listed in your Char Info section.