Modern Warfare 2's story was just awful in every way...in a well written story, every death of a character should be meaningful and preferably foreshadowed in some way (the best foreshadowing being the kind you only notice when you visit the material again). Character actions need to be consistent at the least, and preferably logical in context.
Modern Warfare did that: the death of each main character was at least meaningful, and it was often foreshadowed. By contrast, none of the nations and few of the characters acted logically, and most of the character deaths were meaningless. It was entirely Grim Jock.