If there’s no cohesion between the music and the lyrics, your song won’t reach its full potential. By matching lyrics and melody, your idea will be communicated more smoothly and with a naturalistic style.

Doing this will give your audience a better feeling for the emotions that inspired you to create the song in the first place. It will give them insight into your intent as a songwriter, and that can be a very powerful thing. Check out this post from Songwriters in Seattle for more information about how to match melodies and lyrics.