One thing I think that you guys are missing with these 'marketing deals' is that they're really good at maintaining a mindshare for a console. If every couple of months a new game is getting TV ads with the PlayStation symbol at the beginning and the end, that's putting the system in people's minds constantly. Batman? Oh cool, yeah, PS4. Metal Gear Solid? Looks neat, and it's on PS4. Battlefront? Wow, this looks great - PS4 has all of the big games.
Sony could go out and shoot its own campaigns every few months, of course, but I imagine it's easier/cheaper for it to just partner with the biggest games. And its mutually beneficial: publisher gets additional advertising dollars for their game; Sony gets additional advertising presence for its console.
I do, however, agree with bgamer90, that Call of Duty won't move the needle much for Sony - it's very much an 'Xbox' game these days. I hope they haven't spent too much money on that actually, because I think one thing they've done VERY well this generation is partnering with unestablished IPs like Destiny and Watch Dogs, and that's enabled them to give the impression that they're genuine exclusives.
EDIT: That's all IF Sony has the deal with CoD in the first place. I'm not convinced myself.