I cant speak to CoD specifically, but being able to locate opponents, shots, activity etc by sound is a massive advantage in many multiplayer shooters. I can personally vouch for its relevance in CS, Apex Legends, Arma 2&3, The Finals, DayZ, and Battlefield.
For your viewing pleasure I leave you with this Viva La Dirt League skit: https://youtu.be/sC8qtyGoGZw
Unfortunately, the only hardware component you can actually download is RAM. And increased hardware prices are going to be the primary cost factor.