You have about 3 minutes to tell set up a scene, introduce the characters, explain the situation, sell the emotion, tell a story, and cause the listener to want to hear the song again and again. You also have about 30 seconds to grab the listeners' attention to an extent that they will even listen to the rest of the song.

If you can accomplish all this and still have superfluous lines in your song, then you are a better man than I.