But the word artistic, or art, means design if you take the old greek meaning for it. Things with design have structure and follow some kind of rules. To make poetry without ANY rules is kind of dumb to me, because it's just anti-structure, or chaos. Children could make poetry without design easily. Rules don't necessarily have to consist of rhyme and metre either, they can be very complex and you may have to look for them. Anyway, enough of that, Opeth's lyrics could easily pass as poetry if you ask me. I am, however, much more of a melody person, and I think it matters much more how you say it than what is said.