I searched for a topic about this and didn't find anything, so here you go.
Different skin tones would be a nice addition to the game and it should be easy to implement. Take the existing hearthling skin texture, darken it a bit and there you go.
Dark skin wouldn't fit the game's setting but let's face it, H&H takes place in a fantasy world. The campaign cap has no place in ancient Europe yet it's in the cash shop and nobody minds.