We want to give the player complete control, because there are very high stakes in combat.
Morale plays in, you take a rookie out there and he faces off against an alien, you could lose that rookie, he could completely panic, lose his shit and throw a grenade and everything goes to hell.
On top of that the most important element is that your soldiers can die in combat, and there's
no handwaving, we don't do any hand-holding, when your soldier dies it's permanent, so the player has high stakes and that's the reason we give them complete control, the reason the game is turn-based... the stakes are incredibly high, there are real consequences there.