Sur(tune) in Music is Essential

Do you think Sur(Tune) is essential in Music. I had a hot discussion with some of my friends few days back where the result went 50/50. Some says SUR is not necessary if you sing with feel. If you can connect with the crowd you are a hit. I say, no matter how much you sing with feel, if you don't sing in SUR you can't connect to the crowd. Please share your comment.