Do whatever you want to do, the world is your burrito when it comes to songwriting. I mean, for instance, someone like Bob Dylan obviously thinks that lyrics are of the utmost importance in a song, but many pop singers and really popular music writers don't feel the need to make sense with their lyrics at all very frequently. Like the Gorillaz, or even Lady Gaga, or the Black Eyed Peas, I mean frequently their lyrics don't make too much sense outside of the song.
The difference is if it was a poem, you might not read it, that's what I'm saying. If it was just the music alone, you might give it a listen because it's interesting frequently. But if Bob Dylan wrote a poetry book, you'd probably read it. However, if it was just his guitar playing alone you might not listen to a lot of it because it is just chords on a guitar and a harmonica. So those are just two different philosophies about music and lyrics. So just follow your nose.
But I would say DON'T LIMIT YOURSELF! If you want to be great, at least be aware and able to do everything you think you might use. So don't limit yourself if you think it's not important, just learn it anyways. It's like music theory.
