As HecarimOP said, the SMGs are just as bad though. I remember previous CoD games where the balance between the SMGs and ARs was much better. It's a shame, because some of the assault rifles are really fun guns, but they just don't stand much of a chance in any sort of close to mid-range fight against a decent player who is using an SMG. There's always one gun class that is seriously OP in CoD games though, they never seem to be able to get it right. In most of the MW games it was the sniper rifles, now it's the SMGs and to an extent the shotguns.
In my opinion they just need to slightly reduce the stats of the VMP, Vesper, Argus and Brecci and this would be a much more enjoyable and balanced game. Also, remove cheap kill weapons like the war machine.