The Coalition Provisional Authority in Iraq originally had to print a new batch of dinars that still contained Saddams image at the onset of their organization. While they moved to eventually create notes with the former dictators image, there was much discussion on denomination and guidelines to creating new currency as the Iraqi dinar exchange rate fluctuated.
Since the currency was devalued in practice, the smaller denominations became popular on the currency market for collectors. Buying Iraqi dinars is legal, but the initial speculation on its value may have been just that, speculation. The dinar could have been replaced with the Euro, dollar or various other types of currency when the coalition was deciding what to do about dinar speculation or fluctuations in value.
It has been argued that it was a good move to not link the dinar to the U.S. dollar, since that would have further linked our stay in the country and it would tie the currencies of an oil exporter to that of an oil importer. Since the price on oil can change drastically with any kind of economic or political event, the wages or fees tied to the dollar would not have been advantageous to a new government.
In the original currency exchange from the Coalition government, the Saddam dinars and the Swiss dinars were vastly different on the Iraqi dinar exchange rate. This did allow the new government to back up the currency that wages and commerce was completed in. It also eliminates further issues with switching to a new currency later in the evolution of the new Iraqi government.
Regardless of the history and process of creating a new stable currency, the notes may make fine collectibles for curious history and geography buffs. The fact that the different denominations are readily available at a good Iraqi dinar exchange rate may propel the collecting of notes.