There are two types of people who like Tarantino movies: those who like the dialogue and absurdity...and those who just like seeing people get scalped. I hope you're in the first category. Unfortunately when you sell a product primarily to kids the kids will want to watch (or play) someone getting scalped (or doing the scalping) for no other reason than that it is "cool."
I can't say i'm personally there explicitly to see violence outside of the amusing frame Tarantino uses to present it, but who cares if some people are? Even ignoring your oversimplification, shaming people for having a fascination with violence, sex, etc, doesn't accomplish much, and the former group alone justifies the existence of Django in its current form. You might find it distasteful (and that's fine), but that doesn't mean others can't appreciate the value something unpleasant can add to the experience.
I'm not going to discuss the general 'think of the children' angle. I think it largely just deflects responsibility away from parents, so we'll inevitably end up going round in circles until one of us gets bored :p