Great response! Thank you.
Anywho, I don't disagree. Playing the campaign in coop would absolutely ruin the narrative aspect of the game. No doubt. And I haven't once tried to say otherwise.
What I just simply DON'T get, is how any of this would negatively affect the actual single player campaign. It's literally just another bonus you'd unlock at the end. The story would still be there. It would be the exact same from start to finish. You would play it alone, cry when someone dies, laugh at the banter, whatever. The only difference between U4 with bonus coop and U4 without bonus coop would be that AFTER you've done this, you've experienced the story exactly like ND wanted you to, in the other version you could play it again, but this time with a friend.
I just simply don't see it. It's just another bonus at the end to me. Just something to get a couple of more hours out of the game. Seeing Nate 2 stumble in the background during an important character's death wouldn't negate the real emotions you felt when you first saw the scene. It would be like... Maybe a bloopers reel in the extras of a DVD. I think Gurish used it as an example, actually. If you wanted to preserve your memories of the story, you obviously wouldn't want to watch the bloopers. And you wouldn't have to.
It's existence would have 0 effect on the story experience.
And I don't understand why the fact that you COULD watch them would make the story any worse.
Of course, that said, I simply like having more options. ND crafts good stories, but I don't think of them as these untouchable art pieces that should never be tainted in any way. And if someone does, I don't understand how they're okay with all the other bonus stuff you unlock when you finish a Naughty Dog game.
e: sorry, I tend to get wordy sometimes without actually saying much.