1. More jam on your face. The jam was totally realistic and helped you calm down in the middle of combat by blocking your view of the chaos.
2. Kill the player's character in the single player 20 times. And make all of them unpredictable plot twists that make no sense, since that will totally make the plot better.
3. In addition to heartbeat sensor, we need a motion sensor. And a breathing sensor. And brain activity sensor. And they all need to be blocked with separate perks.
4. A perk enabling 6 weapon attachments at once. We wouldn't want the players to not be able to use all their lovely sensors at once.
5. More imaginary weaponry, like the short range teleportation device attached to the knife, the flesh eating jam bullets and the long lasting EMP. Maybe a chainsaw with a teleportation device or would that be too much of a rip off?
6. The killer rabbit as 2 kill streak. This award would continuously massacre every player on the map for the rest of the game.
7. A spawn system that locates the enemy team, and spawns the whole other team in front of them. In MW2, spawn killers actually had to get behind the spawn point. MW3 should totally make it easier.
8. Last but not least, bring back a rocket launcher that can be used as a map destroying suicide weapon. And don't patch it.