The only reason we KNOW what the lyrics mean and think they're obvious is because the DT guys explicitely explained the meanings for each and every song. That makes it, well........ obvious.
Otherwise I'm POSITIVE that we'd be arguing this until somebody got shot. Conspiracy theorists, cover band guitarists, and ex employees the world over would be suppliying their 2 cents (I could retire on the proceeds). There would be hundreds of threads with thousands of hypotheses about it. Now that's the truth!