Its hard to justify Amtrak charging baggage check fees. Baggage is allowed, in huge quantity, to be carried on. The long distance trains offer checked baggage, in part, to reduce crowding in the coaches. If Amtrak wants more revenue, they'd be better off attempting to get UPS, FedEx, or USPS contracts. While I fully understand why David Gunn made a sweeping gesture to the (understandably) pissed off freight railroads in the form of a reversal of the ExpressTrak policies of the idiotic walking ego, George Warrington, the freights wouldn't mind Amtrak handling half a baggage car full of first class mail.
At that time, it was imperative to placate the freight roads in a big way, and killing the entire concept of Amtrak hauling freight by contract was probably the right answer. But now that its been five years since the last Amtrak freight train left the depot (the Kentucky Cardinal, Lake Country Limited, and Three Rivers were primarily freight trains, remember- sometimes not even carrying passenger cars!) I think it would be ok for Amtrak to regain the USPS contracts that they were specifically, by the Amtrak law, allowed to haul.
The problem, of course, is that in the ensuing years USPS has had massive financial problems, has reorganized, and quite a few of the facilities for handling railmail have closed.