Completely disagree. Why? Because Assault rifles are the god class in cod, and in infinity wards games the other guns are beefed up to try & match the ARs. SMGs dominate close range but take significantly more bullets at range, snipers get quickscoping, shotguns have better range than in blops, LMGs are basically crappy Assualt rifles (Pros: better penetration & clip size. Cons: slow movement, reload time & ADS time) and for this are a rare sight, but are still just about usable.
In Blops the gap between ARs and the other classes is even more evident.
I'll pull a pathetic realism argument here- the MP5s effective range is 200m, which is just over 2 football fields in length. The longest sightlines in all cod maps is usually about that range, to balance it out for gameplay they simply make it take about 6-10 bullets to kill a man at range which is fair enough. Assualt rifles & LMGs is half that amount.
@OP: Silencer damage reduction is fine for three reasons.
1, when using a silencer you do not appear on the map (Obviously)
2. With a bolt action you would be very hard to hear/notice tracers since you only fire 1 shot at a time, combine this with a good camoflauge spot & it would be overpowered if you could 1 shot everybody.
3. Imagine all the cry babies about silenced quickscopers. (although quickscoping is currently balanced, the cry babies would probably be justified if silenced 1SK quickscoping existed)
When I want to stealth snipe I use semi-automatics since it usually takes two shots to kill anyway, yet I am still slightly noticable from the spraying sound & spray of tracer rounds across the map, a fair trade. Also to the person complaining about silenced snipers at close range- it is also fair being weaker because a silent quickscoper would probabably be overpowered. That is another thing quickscopers have at a disadvantage- you cannot put a silencer on. It is balanced how it is, if you want a silencer on your snipe use a semi-automatic. The RSASS, M21 & WA2000 were great with a silencer, but 2-3 shot kills unless headshot, which is balanced.
TL;DR: Silenced snipers are balanced how they are, except for in blops- silenced PSG1 took 2 shots to the head to kill lol.