For me, I really like how they plan to do the co-op, because I haven't seen co-op quite like that before. It's nice that it's optional, and nice that you appear to be able to go your own way. I love playing co-op with my buddies, but I don't like being attached at the hip so much - sometimes it's more fun to do your own thing. This sounds like it might be the perfect mix of the two.

And hey, possibly they'll make it so that you can play Carver's side of the campaign? Or have a friend over to play him split-screen?

EDIT: Just realized... why can't you play online? You appear to have an internet connection.