So we have a pretty dynamic contextual music system. It responds to a multitude of parameters (it's actually sets of huge 12 channel music files with overlays being triggered based on gameplay).
Enemy type
Enemy proximity
How many enemies
Whether or not you are being targeted
How much badass stuff you are doing (headshots, abilities, melee)
The system aggregates all of those and controls what is playing based on them.
Then on specific missions where we know exactly what is happening we script specific music sometimes. So it's something we can tune in live service, and even based on power level/difficulty setting etc. I will pass this feedback on to our music team and see what we can do!