How are you forfeiting everything? You will get all your miles back after cancelling (they no longer charge the $150 redeposit fee that used to apply for those with less than Plat status) and can then reuse them for the one-way award booking. Since you apparently booked an award with a roundtrip booking requirement to save miles, why should they let you keep half the award if you no longer meet that roundtrip booking requirement? It's no different than booking a revenue fare with a roundtrip booking requirement and then expecting to get a credit for half of it when you cancel one direction and you no longer meet the roundtrip booking requirement. I believe all the other majors have the same policy (if you go on WN board, you will see they always recommend booking trips as one-way's for this reason).