I would second that. I rewired my boat last year and had a chance to see what untinned copper wire looks like (granted, after 35 years on the boat). It was corroded and green everywhere along its length, virtually on every strand. That included wires that were completely isolated from the water, in dry compartments and all the way inside. It was a total mess.
While I don't have similarly aged tinned wire to compare, I did see tinned wire from 20 or so years back and it had none of these problems.