That's the attitude! On a different railway more hard pressed for cash they would have lived on, probably relegated to slower operations. The 'killer' in this specific case has to be the consistent success of the Fowler 2-6-4T and the Stanier development that followed it: work on 'the problem child' or replace with 'as good as it gets'?
Nevertheless makes a handsome model, and bound to baffle a few shown carrying BR livery...
Addition to the 'why not' possibilities: Stanier arguably should have taken up the Garatts for review, to extract the full performance potential from these expensive relatively new builds; 2-6-2+2-6-2 perhaps? "Summer holiday traffic use saw the rebuilds successfully working the heaviest trains on 60 mph schedules, that previously required double heading, but now only required a second fireman on the footplate." Go on, you know you want to...