Dylan's "Hard Rain's a'Gonna Fall" didn't rhyme. It's a fantastic song. You write one that good and no one will care. However, I'll toss my 'vote' with Alaska Mike on this. Rhyme allows people to try 'n outguess the writer--a game for them to play. Also, part of the art/craft is saying exactly what you want and having it scan AND rhyme, IMO. Best wishes and best luck be with you.