> I've always wondered why, if the alien was smart enough to mimic/occupy a human, why it just didn't communicate that way and say "take me to your leader" or some such.

"This thing doesn't want to show itself, it wants to hide inside an imitation. It'll fight if it has to, but it's vulnerable out in the open." - Macready

It's too scared to do that, and it knows it can win if it hides successfully in people.