I know the quick scoping issue is divisive in the Call of Duty community, so I'll state my position first just for the sake of transparency. I do not like it. I argue it makes most sniper load outs entirely too cheap. The whole point of snipers is to have excellent long range capability. But with quick scoping, their short range capability makes them essentially a one hit killer in any and all circumstances, grossly unbalancing the game where the mechanic is present.
Having said all that, I wouldn't point out Modern Warfare 2 so much as Modern Warfare three as the prime offender. Black Ops II is pretty bad as well, but in MW3, it was epidemic. Cheapest game mechanic I've ever seen in a shooter.