An example of using a score to provide a musical context in which the sampling artist then overlays his own narrative would include M.C. Hammer lifting the musical score from Superfreak for Can't Touch This . In this case, the entire song comes over intact, minus the lyrics, which are then added anew by the sampler. In this case, MC Hammer simply took a song by Rick James and put his own rap over it. The narrative is there to supply the concept of the song. Music provides structure, the technicalities such as timing, rhythm, length and tempo.
Music is the emotion, lyrics are the intellect.
The separate elements of music and lyrics are also processed differently by the brain. The difference in function is illustrated by the fact that it is quite common for different people to write the music and the lyrics. They can also survive independently. Sampled narrative elements tend to be from different contexts. So far, most techno tunes that sample media just sample one line from a movie and then repeat and riff off of it.