It may not be as easy to do as some may think. States are making a LOT of money on "vanity" plates with different "themes". It would be hard for them to give up the revenue. There are a lot of "charities" that have "deals" with the states that use vanity plates to raise money. Everyone wins on those plates. States went to rear plates only because it cut the cost of plates in half.
We plan on buying the new Michigan Ducks Unlimited Plate in July when we renew our plate on the pick up truck. It is another "win win" plate, both the State and Duck Unlimited making money on it.