Do you remember the single player mission where Ellie and the perv were fighting waves after waves of Clickers? It was so much fun that I kept dying on purpose, only to replay that checkpoint again.
Naughty Dog has great experience with co-op games from the Uncharted games, where you play with your friends as a team against the AI.
Why is the horde mode missing in multiplayer mode? That would be so much fun.
The NPCs would be half so intelligent as in the SP.
U2 Coop: 100 Soldiers spawning on 1 or 2 Points and you can strife your AK around the Screen.
U3 Coop: Less spawning NPCs. But still not really clever. Just shoot and go behind cover.
TLoU SP: Many Clickers. They run. And you shiv. And... Simply not possible to make a Coop Mode. Finding Supplies, Craft Items. Hm, they could nerf the graphics like they did in U3 MP. Also it would be to easy to get Parts.
TLoU MP is a competetive thing. You're searching for Supplies, you have to kill other Players who are sitting on a couch and do the same like you. Pretty hard to explain, Man.
The only thing I understand from this thread is the title.