Game designers could do something about strafe-dodgers or the bunny-hoppers if they wanted to, but the thing is it's accepted as
classic gameplay now by a large part of the gaming world. So run & gunnin' with all the twitchy-moves has become mainstream, and it's just seen as another gaming skill to be used by millions of online gamers. Do I personally do it, no, but if a game system allows it (as the OP mentioned, it is 2010 after all), then titles that allow these unrestricted moves must be doing so by intention.
So what to do about strafe-dodgers or bunny-hoppers? Well some shooter designs exact an exhaustion penalty for rapidly and repeatedly hopping for instance, and the same thing could be programmed for strafing maneuvers also.
There's obvious ways to attached an exhaustion penalty to doing body movements repeatedly with the ease of mere keyboard flicking, but again, this stuff remains possible in many games because game designers don't want to offend their most vocal, devoted, and/or skilled users.
Fact is, some of the most popular shooters will require reverse-engineering to remove these unreaslistic gameplay features, all caused by flaws in their original designs (and which of the powers that be would want to admit this, and be yelled at by their devoted fans for doing something about it all now anyway).