Ummm. My friends and I can just pick up and play Battlefield and Halo. Simply spawn in a game, for battlefield pick a class, then go out and shoot stuff. If your talking about tactics, a lot of people find tactics easier than run around and shoot anything that moves. My family included. Halo is just as simple as CoD to pick up and play, I'll give Battlefield a bit more difficult due to having to know how to select a class >.>, in both you spawn, run around and shoot stuff.
In all honesty, Games like Quake and Unreal were even easier than CoD to just pick up and play, does that make them the best multiplayer shooters? I guarantee that due to the ability to actually dodge some of the bullets in those games it was easier to live and get kills in than CoD.
And I also beg to disagree about CoD being at all a pick up and play Multiplayer game. Singleplayer, sure, but any game is. Multiplayer on CoD, join match, get headshotted the second you spawn. Respawn. Same guy comes back around corner, sees you, shoot you. Respawn, you teammate killed them, you walk around corner, some guy sees you, you shoot him, some sniper shoots you though and you die. Respawn. Another guy has come around that corner and is kills you the second you respawn. Respawn. He's not there, walk around corner, see someone, crouch and zoom in to shoot them, start shooting, they get hit by one of your shots, turn around, then kill you.
That is not pick up and play. There is a definite style of playing you have to pick up to play CoD, much the same as Battlefield and Halo. When I first played it, I tried to play it semi-tactical, knowing it wasn't Halo or CS, but still thinking Tactics could make a difference. See above for what happened.
Yes, I may be a n00b at CoD, but it was not an enjoyable experience, and the fact I had to pick up on a play style to be able to play even semi-effectively proves it isn't a pick up and play game. Hell, about the only time I actually got a higher than 1/4 KD was in the pre-fight knifefights, where I'd use Ballistic Knives as they are still technically knifes.