I think you missed the part where many inhabitants of this thread declared their love for vests.
What is a ska kid, anyway? I was in high school three years ago, and don't know what you are talking about. I have only seen that term since then.
I think the progress of my idea went something like this: Oooh, I like that dark red button-up with the black, looks a bit formal even. Then, "Hmm, I like the way vests look." Then, "You know, if I did the formal vest, shirt, tie, slacks, and shoes with the right trench coat, that would be almost a suit, but a bit more my style."
So, pretty much, the vest isn't essential, but it should make the outfit look a bit sharper than just a dress shirt and black slacks.