Another thing about the footsteps in the MW2 beta is that they are very loud on a map which is a good test environment; the hotel one basically. This combines interiors with some wood or carpet flooring, stairs and upper levels. Some people are saying they aren't an issue when playing the farm or market map and this is probably the case, but only by virtue of the amount of exterior and quieter surfaces. The more indoor maps they have in the final game with upper areas or non-concrete surfaces, the bigger this problem will be. Personally I didn't have many issues with footsteps when I played but that was only because I played on the hotel map about 3 times but if you have 4-5 maps with this problem then it will turn into something more significant. This has already caused huge problems in Warzone 1 where you could literally hear people on the top floor whilst the other side of a 10 storey building for instance.
There are also very smart players who can literally configure their headphones to only pick up on certain elements or enhance others so if they want to soundwhore to the maximum potential then they will to a devastating degree. The dead silence perk is very OP but a staple of the series and it could've been blended in a tier where users could have chosen that or the ability for their gunfire to not show on the minimap - either perk representing an advanced ghost-type one in a competitive slot but instead they've protected people loud with their guns and punished those that move around the map with their feet!