You don't want it to have an entirely new feel though, because then it begins to stray away from the original ambience of D2 that was part of the reason that we liked it so much.
Of course they should revisit some of the old music and possibly do something with it. I ain't much of a composer, so I don't really know much about that sort of stuff.
Tristram song should be there, its the theme, the style should be the same from d1 and d2, it gives the feel if diablo. MATT UELMEN should be the one who does the music, he did it for d2, he should do it for d3.
Of course they should revisit some of the old music and possibly do something with it. I ain't much of a composer, so I don't really know much about that sort of stuff.