One of the things a player will pick up on very quickly playing Call of Duty: Modern Warfare is that the game is all about split-second decisions and fast reactions. In a game where one kill can be the difference between an awesome Juggernaut killing spree and a long evening of disappointment, reaction time is something that must be held sacred. Unfortunately, some players are experiencing trouble on that front.
One of the major innovations that came to the franchise with Call of Duty: Modern Warfare was cross-platform play, which allows players on PC to compete against those playing on a Console. For optimization and fairness purposes, there are small differences between the two versions designed to bring players to about the same level of performance no matter what they are playing on, but one of these differences seems to have been taken too far.
A test by Reddit user u/J3RRY__, who was good enough to record video evidence of their finding, compared the turn speed of a player affected by a stun grenade in Call of Duty: Modern Warfare when using a controller as opposed to a mouse and keyboard. The test showed that a controller, obviously used more often by a Console player, allowed a player to turn around twice as fast as a mouse. A further test showed that even upping the mouse's DPI did not do much to alleviate the issue, not shaving remotely enough time off of the turn to be comparable. In a game where a glitch that blinded players was cause enough for complaint, a feature that hobbles them has drawn a huge amount of ire.
With a Controller you can turn twice as fast while stuned compared to mouse & Keyboard independent of DPI from modernwarfare
One of the major sticking points for PC players is not the discrepancy in turn speeds itself, but the response, or lack thereof, from Infinity Ward. Call of Duty: Modern Warfare is not exactly a game free from problems, and it has certainly had rockier glitches than this feature, but those were often addressed promptly. The complaint about the turn speed has stood for several months at this point, and no answer has been given, leaving players wondering why the devs have been silent about what is clearly a well known and widespread issue.
To an outsider, this may not sound like too major of an issue, especially since it seems that it is tied more to a controller than the PC itself. As a feature, it was no doubt added for balance issues, and the devs lack of an answer means it will probably stay. There's no telling how playing COD using the DK bongos would affect flashbangs.
As mentioned earlier, speed is the heart of Call of Duty: Modern Warfare, and anything that hampers that speed is met with extreme caution by all players. Something that gives a distinct advantage based on a peripheral a player may or may not have is something that will be frowned on almost universally, and there is no reason to expect that anger will vanish unless the feature vanishes with the upcoming Season 2 updates, or, preferably, before then.
Call of Duty: Modern Warfare is available now for PC, PS4, and Xbox One