Allow me to translate.
Co-op play for the entire main campaign would have "really broke the cinematic experience, took the immersion out of it, out of the story and the pacing and everything we'd spent so long crafting,"
If we offered free co-op through the campaign then no one would pay extra for more co-op "challenge" maps, because we at Activision are greedy pr!cks you'll get a co-op experience but we will sell it to you in installments. Also its MW2! You're all a bunch of crack wh0re junkies and you will buy it any way.