Well, skins are completely separate than allowing users to use any color they want to post in the shoutbox...
imagine, your theme is a blue and white theme, and you have member posting in fuchsia and pink in the sidebar which throws your colorscheme off... add to that ad islands where you WANT peoples attention and you're drawing your real estate to some meaningless random conversation versus content that would be where you want users to look...
I can see where you'd like it, I'm just providing reasons why it would be distracting to have... personally, if it's added, i'm just saying i want a way to remove it...
