I have the opposite opinion about Rammstein, actually. I find that the later stuff generally works much better, because the obvious bleeps and bloops of Herzeleid and Sehnsucht were too typically "industrial" sounding and distracted from the feel of a medieval-fantasy game. I don't mean to just argue, but I'm not sure how anyone could listen to the throbbing synth in the verses of Sehnsucht and think that this stuff was somehow less "industrial" sounding than their later stuff, and the bouncy guitar riff at the beginning of Eifersucht and the laughter, for example, strike me as just being silly. Their later sound became a bit more sophisticated in its incorporation of electronic noises, though some tracks are too oddball to really be used much for D&D (Amerika, Keine Lust, Te Quiero Puta!, etc.).
Different strokes for different folks!
Part of the problem with a lot of movie scores is that the music is molded too well to the action in a scene - a rapidly swelling crescendo might perfectly match the action as a building collapses and the heroes of the film try to escape, but it might just be really distracting when all you're trying to do with your D&D music is set the mood. Also, some themes become so iconic that the players won't be able to associate the music with D&D because they'll constantly be thinking back to the film or videogame in question.
Sometimes, though, using a well-known rock song can have the opposite effect for a dramatic moment: players recognize the song and have some emotional connection to it already, but don't already have it associated with a "scene" - so by tapping into their feelings about a well-known song you can sometimes heighten the intensity of a moment. This works especially well if the vast majority of your soundtrack is instrumental, subtle, and/or unknown - the moment you decide to spring the iconic rock song on them suddenly becomes a standout moment, something to remember.
