A few things. First, I realized I've never put on a case on any of my iPads in the past. Second, I looked at my black iPhone 5 and it still looks great and I've had it since launch. Third, I really enjoy using the mini without a case. It feels so good in the hands due to its thinness that I just can't put a case on it. I'm careful with it as I don't want to scratch it, but if it happens, it happens.
Why have a case on something to keep it from scratching if you won't ever see it due to always having a case on it? Just knowing that it isn't scratched? Personally I'd rather use the device "the way it was meant to" rather than worrying about scratches. My mini is covered with insurance in the event I drop or spill something on it, so I might as well go without a case.
I now use it with only a Smart Cover so it has a stand if need be. If I'm taking the mini somewhere, I throw it in a Nedrelow Sleeve.