I don't think it would be a waste of money in all cases. For example the traveler who is a few trips short of Platinum could make it work quite well. The MQM's earned could push that person from Gold to Platinum and open him/her up to a 5 day upgrade window vs a 3 day window. How much is that worth? Unless I do not completely understand (a very distinct possibility) a T fare could get that person an upgrade and save over $2000 over an F or Y fare purchased late.