It appears treyarch want to control the way you play your FPS games.  Quick-scoping will be deliberately gimped in Black-Ops, the developers have decided that quick-scoping is a cheap way to play and will do what they can to stop it being used in their game.  for more info visit http://n4g.com/news/632888/call-of-duty-black-ops-quickscoping-has-been-banned

source http://n4g.com/news/632888/call-of-duty-black-ops-quickscoping-has-been-banned