Mhhh... posting with tinypic doesn't do the image-quality much good, I see. The original is much less blotchy. If you want to see the 'good' result, you should probably give this method a shot yourself.
Why I didn't pull the black slider in, well, 'matter of taste', mostly. This is an attempt to create an effect that occurs when developing 'analog' film. One should consider both film grain and the way film is developed... My logic is that on paper 'white' is the color of the paper where no silverhalide crystals are triggered. So there can be 'pure white' without any grain (except maybe for the papers structure). The blacks are always composed of triggered silverhalide, so grain will be visible more. As far as I understand film development, the grain also gets larger the darker the tone gets, which leads to 'plugging' at a certain moment. Theoretically those plugged area's would be pure black. There would be logic in pulling the black slider in a bit, though I think the negative film also has it's own graininess that would prevent a black from being grainless.