Dylan wrote that song in the early sixties at a time when the civil rights movement in America was growing larger with every call and that was where his thoughts for all of his greatest protest songs came from, he was living with what was going on in America 24/7 and the World and that as a songwriter was probably all he could think about and I'm almost certain he didn't write that song in a day but thanks to the civil rights movement he found his audience and the Freedom to write in such a poetic style, as a songwriter he grew with what was going on around him even after a few years when he went from acoustic guitar to electric he might have lost many fans during that time but thankfully he never lost his freedom in his thoughts to write what he really wanted to write about also i would say he didn't write according to the rules, here a link to a article about him that maybe you might find interesting.
http://www.redpepper.org.uk/the-politics-of-bob-dylan/I have to say one thing i don't like in your post is this (Although I feel I could never write something that "poetic" if I was trying my hardest to get a set message across.
This is because I'd get annoyed that it wasn't good enough or it wasn't portraying the message correctly) my advice is totally ignore those thoughts.
Sometime when we write lyrics we don't write them until we read back what we've already written take for example if you want to write a protest song then that means you already have thoughts of what you want to write about, the same can apply to any subject you want to write about and as i said, sometime when we write lyrics we don't write them until we read back what we've already written.
Happy New Year to You and All.
