@Beastwolf: They're styled as scouts / ambush units rather than proper soldiers so it makes sense that they like to use overwatch rather than try to charge you or something.
@Elyseon: pretty much the reason i always hated the missions which had a turn limit for an objective, because the games like "HURRY!" "oh, you're men are dead because you rushed blindly around a corner and into 5 aliens"
@Matthew Martin: Don't forget the part where aliens, especially Thin Men bastards, tend to get insanely lucky with their shots. Even a MEC Trooper (cyborg with limbs replaced by metal prosthetics, riding a giant robot suit for those not in the know) can have trouble against a large pack of them.
@Matthew Martin: Yep, they often are dropped in units in council missions and when dropped they automatically enter overwatch. They also have a oddly high chance of just outright using it if they cant get line of sight but know players are nearby.
What's wrong with me.
Assuming Angie is 1 tile away, and those are light plasma rifles, and she doesnt have lightning reflexes or any skill that reduces chance to hit, if she sprints she runs 2 overwatch shots at 79%.
She'd need 12+ health to guarantee survival on both shots.
@MR. Al: in XCOM, overwatch ends a unit's turn but when any enemy unit moves they take a shot at them. Because XCOM is about using cover effectively, taking a shot at an enemy out of cover is a very good option. The Thin Men shown here were notorious in XCOM EU/EW for using overwatch.