BFBC2 didn't take itself seriously; it (tried to) stealth-parody the whole SUPER ACTION PLOT, ONE SQUAD VS. THE WORLD, OH SNAP BETRAYAL trend appearing everywhere

BF3 wants to try and ground itself with a (relatively) realistic conflict, hence the removal of the BC squad and the inclusion of Iraq. Don't know if that'll pay off but I doubt we'll see any long-lost superweapons here.