NS is a big game, and a lot can be happening at one time. For the alien, they can look around and see where their teammates are, and if they or their buildings are under attack. The marine on the other hand, require just as much teamwork as the aliens (if not more) yet they have no such way to tell where their teammates are, or if their buildings are under attack. True, the commander gets a nice little message saying "your base is getting killed" yet the comm has enough to do, without having to relay these messages to his marines. It would really help marines who were trying to work together if they could see where their teamates were, and if their res towers or other buildings were being attacked.
"Marines have such poor pathfinding" -Hida Tsuzua
"When the going gets tough, the tough go cyclic"- Army Ranger Clay Othic, aka "Little Hunter"