Connecting to the Past
I think that today's Jewish musician should be able to interact with the music of our past. This concept can easily be taken as far as the oldest melodies and lyrics. From Darius Milhaud's setting of the Shabbat shacharit service in the mid-20th century to a variety of Kol Nidré arrangements to Idan Raichel's visions of Song of Songs and Psalms, interacting with the cultural production of our people's past is an important component of new art.
One issue we may face today, though is how to access the sounds of the Jewish people's past. Sure, libraries might have scores for collections of niggunim and there's people chasing down old records, but these media likely aren't easily accessible to today's Jewish composer or lyricist. Without our musical heritage contributing to those of our generation who are currently producing musical output, we risk severing today's Jews from works of the past. Fortunately, there's groups like the Breslov Bar Band (find their track on the right sidebar!) giving new voices to old melodies.