The skins of nuts contain lots of anti-oxidants, vitamins, minerals and fiber. They also add texture and flavor to the nuts and to nut butters. The 'brown' on pistachios is dark red anthocyanins, potent ant-oxidants also found in peanut skins, especially redskin peanuts(as well as in blueberries and other red/purple/blue/black fruits etc......What? You skin your peanuts too?!). You're throwing away a lot of the goodness and wasting time needlessly. ....it's like refining wholewheat flour to white flour or brown rice to white rice. You end up with rubbish that looks pure and white on a plate......not a healthy product. Like Frank Sinatra's song..."All or nothing at all...."