In classical music, concertos and symphonies are actually several tracks (usually 3-4) and there may be several pieces on an album (that might consist of up to 20 or more tracks).  In using the random play and shuffle features, it would be useful to tie tracks together that belong together.  Although tying tracks together is possible using the playlist feature, it doesn't appear that playlists are integratable into random plays and shuffles with individual tracks (although adding this functionality might allow for this request to be possible).