I'm not sure I like the idea of people being able to create their own skins to be honest. I don't think it would really fit well if people were able to walk around in a tuxedo for example. It was also easier to accomplish skins in MC as you just wrap a low-res texture around a few fixed shape blocks.
For me personally, I'd prefer to enjoy the game by seeing other players with the originally designed skins, which will make the game more immersive overall and less 'gimmicky'. From what we've heard, there should be enough variation in wearables with tinting and styles to make sure everyone is fairly unique (although probably not so much at the start!). If we're able to tint our initial character skin colour in the same way (unconfirmed), it'll give a additional amount of uniqueness from the outset.
Personally, I wouldn't be opposed to seeing real money purchasable skins which could give you a new variation for a particular race. They wouldn't be game breaking, and this could potentially mean an additional revenue stream that could be added to over time, which will broaden the variety of skins throughout the lifetime of the game.