Those of you who say that there's no gameplay reason to include this scene or either Fucking retarded (unlikely, but possible) Or completely missing the point, The cutscene right before adds context, and
Highlight to read:this event is THE event that sets the conflict for the entire game, Nothing else, just this.
To say that's not important would just be plain stupid given the cinematic nature of the series.
I mean, in the first game you were the unarmed civilian that got fucking assasinated to set off events. Not to mention the scenes where the resistance fighers were being assassinated at the beginning of the game. Infinity Ward includes levels that serve no purpose other than to tell the story.
And how come nobody was so upset after the nuke that killed 30,000 troops and some staggeringly large number of civilians in the first game? the next mission was JUST crawling over your own ally's dead bodies, before dying yourself. I guess that wasn't really necessary either, according to you guys' logic.
tl;dr: Context. You're missing it. This is nothing new, people are just seeing what they want to see. Stop being girls.