I agree with the OP, and the advanced combat missions need to be revised, but not for the stated reason. Combat and transport missions are in the same boat here, where the time required to complete the mission (not the cost of the ammo) is out of balance after level 1.
The dev's are working on adding in a time bonus for missions, so completing them faster gives you more reward. Which is all well and good, except that in many cases the missions seem balanced around multiple players in a squad, and not for solo play. Which, if that carries forward, the combat missions will be even less effcient to run as a solo player, since small groups will be needed to get them done 'faster' for the bonus.
There needs to be seperate assignment lines for solo and group combat assignments. This is really the only assignments that can be improved by adding more players, that is 2 players can't run a transport mission faster than 1, same with mining and scanning missions.
Tl;dr - Encourage group play with assignments balanced around multiple players, but add higher level assignments that solo players can complete too, with appropriate rewards for both. Meaning if it's easier/faster, then the reward is less, but it's more than a lower level assignment in terms of NIC/hour.
Edit: FYI, the reason I mention transport is for the same reason, players will continue to run the 'laps' of level 1 instead of going to level 2 because the NIC/hour is better on the laps. Only indy looking to raise rep bother to go to 2, or beta players moving through to 5/6.