Not to mention the reduced stress on the shop crew as they would be afforded more time to work on the locomotives (and other equipment.)
If one goes down now, they have to work feveriously to get it back to operational to make the daily trains. The more resources, the easier it is to do and less stressful it should be.
Also, having the locomotives operational means far fewer cancelled trips due to lack of motive power. Nothing hurts a railroad as much as having to turn paying customers away. Having problems on the road is inevitable of course but having additional power available will reduce these failures (having the track in good working order helps too.) The C&TS is heading that way. Cheers!