Instead of burning a billion dinar notes, the US government might have just auctioned them on Ebay, where they are currently selling for $1 a piece. Of course the new supplies would have driven down the price, perhaps dramatically, but wouldn’t that be better than burning?
Of course we are talking about an entity that finds value in bombing and then rebuilding an entire country, so there is an element of absurdity about suggesting that the US government think entrepreneurially. In any case, the whole operation to replace one kind of paper currency with another, printed by the same British firm no less, merely because it had the wrong politician’s picture on it, is silly and wasteful, unless the whole operation was designed to unearth hidden cash. Meanwhile, the currency exchange seems to be going well (here and here)—so far.