Use of humor in a serious song

One of the songwriters last night was performing a pretty serious song and in the middle added two humorous lines. It sparked a good debate, should you or should you not add humor in a serious song. The crowd last night was evenly split.

In this instance the lines fit his personality perfectly. It really fit who he was and his music. They really did a good job of breaking the tension he had built up. However, if I was going to perform this song, those lines wouldn't work for me. It wouldn't fit my personality. Finally, the song was really strong with or without those line.

So the final answer is, it should stay the same and it should change (I could be a politician). The question really boils down to, who are you writing the song for and how will it be used?