Another argument for Auto-combat: in every game there always some thing that is boring to at list one person in the world.
Imaging, that you here and now just don`t like this mission: you don`t like this race, you`ve already seen this ship may times, you killed all the powersources, you just are thinking now about your research...whatever, that can be called 'NOT NOW!' But still you don`t want to lose rank for assault of UFO, you want to get some minimum loot, but you want it to finish as quick as possible. Why not to skip it and not to go to things that you like to do more now?
You made auto-sell function, didn`t you? Because you believed that there is someone who thinks that selling stuff by hands is boring. You can do the same with missions.
Understand me correct - to skip repeating movements I can do super gun, which for 0 TU will blow up all that stupid houses with all still alive aliens in them. But make a special option for it, just one move, - I find that it is more elegant way.