I find it interesting that lyrics often seem like an excuse to sing. People can't sing "doot doot daa" without sounding like an idiot. But when you make them actual words, it's totally fine. In contemporary music, it is very rare to have a song without lyrics. They're basically a prerequisite. But because of that, they have a subtle power.
It's plenty easy to ignore the lyrics of songs. They're just fluff to allow one of the musicians to sing a melody. But, as it turns out, lyrics express thoughts and opinions, just like any other form of writing. And sometimes the thoughts and opinions expressed are serious ones. They can talk about civil rights, world views, personal responsibilities.
People are quoting music lyrics constantly. They're on status messages, tattoos, shirts, tombstones. Pretty much, anywhere you can put text, there are song lyrics. People really care about them. They mean a lot to people. People live their lives by song lyrics. People can change their lives because of song lyrics. People can change the world because of song lyrics.
If you are writing something popular, you can sneak in some education and deep thoughts without people realizing. You can discuss serious matters without the common sentiment of it being stupid or boring. If you were writing something so powerful and so readily accepted, what kind of sneak education would you give your readers?