I actually think that Bungie's advertisements are really good for what their purpose is. which is to place the reader in the emotional place that the game is trying to put them in.
In Halo3: ODST, you're not playing as a Spartan. You're an elite soldier but you're still far more fragile than the people you're fighting and death is your ever-present companion.
You can't, and shouldn't, equate playing a character in a game with real-life regardless of what game you're playing. The game's purpose is to tell a story, to transport you into that world, and make you feel something. After you turn the game off you can go back to your world.
I, personally, take more offense at all those WWII games that came out. Because you have all these kids playing them and thinking its cool without really knowing a damn thing about WWII and how messed up it really was. I tell them to go watch Band Of Brothers and then tell me how cool it was.