It's really nothing new for composers to take somebody else's theme and either rearrange it or slice it up into something else. The remix has the potential to do something similar. If the results so far have ranged from tepid to insipid to disastrous to sacreligious, it's the fault of the people doing them, not the technique itself.
People will make music with wahtever tools they have at their disposal, always have and always will. A lot of kids today don't want to learn instruments and conventional theory, they want to learn turntables, samplers, mixing boards, etc. Although that notion bugs me to no end, I'm more than willing to concede the possibility that things are changing in a big way, and that they ain't going back. Sound is sound and tools is tools.
Remember the touting of Sgt. Peppers as a breakthrough for using the "studio as an instrument"? Well, that was just Round One...