Yeah, and not only should we be able to high five, but instead of dying we should have a bleed out time, where our team mates can rush over to us, pull us in to cover and heal us. We could also have features to make the game more interactive with our team mates like back to back, where any amount of team mates can go back to back and shoot from all directions. And we could have things like co-op snipe, shields, parachutes... Oh wait, that's a completely different game. Never mind.