There are exceptions to every rule. In this case the Commodity in question is the life-blood of modern civilization. Every other nation has to convert their currency to the USD to make crude purchases, hence regardless of wether they want to hold a falling USD or not, the USD crude peg results in an artificial demand for the USD. The peg makes USD the defacto global currency. If that peg should move to the EUR, demand for USD falls and demand for EUR increases. Therefore, yes, it does matter which currency Crude is pegged to.
And to expound further, if there is more USD floating around that no one wants, it loses value and creates inflation at home. High inflation triggers higher interest rates. With high interest rates, companies have to pay more to do business, and it becomes more difficult to open new business therefore effecting job creation. Also with high interest rates less dividend is paid. If less dividend is paid, stocks go down. If stocks go down and you have low job creation you are creating a recipe for a prolonged moribund economy. Well by now I assume you can understand why the USD peg to crude is vitally important for the US economy and maintaining global hegemony.
