Why do you think Marty O' Donnell's nickname is "Marty the Elder"? He's one of the Bungie's most respected employees who's been with the company since the first Halo Game. He composed the music used in all the games and he does a tremendous job at that. Music isn't just a background noise used to gameplay less boring, no far from it. The use of music is to immerse the player in the video games setting and convey emotions that properly coordinate itself with the moment of the game. Some moments you'll want some songs that make things sad or seem hopeless. Other moments when you're in the heat of battle against a huge pack of Fallen Troops, you'll be introduced to an invigorating song that makes things seem a lot more fast-paced, filled with action, and make you feel like such a badass. That's why music is an important aspect to a game and if you can;t see that, then you're just ignorant and not a true fan.