Here's a news flash: No soldier gives his life. That's not the way it works. Most soldiers who make a conscious decision to place themselves in harm's way do it to protect their buddies. They do it because of the bonds of friendship - and it goes so much deeper than friendship.
One of the reasons I did this because I wasn't really looking for another science fiction film was that my daughter can see it. She's 9 and it's really a good film for all ages.