Who needs durability when they are still going to go from the Mint to the Fed to the banks to the business to the public to the jars?
So as to keep the public from realizing that the coins have been debased yet again they would continue the copper plating. (After 25 years there are still a LOT of people out there who think the cents are still made of copper.) You would also want the copper plating to reduce wear on the dies Aluminum is very soft, but it is also coated with a thin film of Aluminum oxide, the second hardest naturally occurring substance. The moving of the planchet metal across the die surface during striking is very hard on the dies. The copper plating would protect the dis.