Overwatch, return fire and such need the following:
= Ability to select the the sector to watch for(i.e. everywhere around, 180 deg in front, 70 deg to the left etc). Being able to order a soldier to cover only a particular side or even a particular doorway can be very important when having enemies coming from different directions.
= Ability to select at which distance(or chance to hit) to shoot. So many times I had soldiers shooting an enemy which appears at the edge of the view range and was clearly too far away to hit, only to have it move in to almost point blank range during that enemy turn, making the already taken overwatch even more wasteful.