Because I like playing my games for a long time?
Yes I often listen TES 3, 4, 5 soundtracks (Jeremy Soule
) even while playing other games like Civilization IV with a friend on LAN for example, LOTR soundtrack as well.
That doesn't mean I can listen to the same in-game music for more than let's say 100 in-game hours, however good it is. It gets boring and repetitive, and it starts to detract from the atmosphere and gameplay experience, instead of adding to it, so I'd rather have clean ambient and effects sounds instead, like the person you responded to said.