This might count as two, but the greatest success for multiplayer is the equality of silent footsteps and ADS times (ie fast ADS, fast ADS recovery, and fast ADS strafing). That way, everyone is equal in terms of reaction times and everyone is on their toes due to the unpredictability of the game coming from silent movement.
Fast ADS, fast ADS recovery, and fast strafing while ADSing should be very quick by default (like if everybody were using quickdraw, stalker, and ready-up). However, each weapon will still have different speeds when compared to each other (SMGs being the fastest and LMGs being the slowest).
The point is that there's more equality when the speed perks (mentioned above) are automatically bestowed to all, plus it makes the game much more faster paced.