I own a heap of DLC, and likely won't play some older routes. However, I would like those route's trains for layering on other routes. It would be great to save on space to just have the option of downloading a route's trains instead of the whole package.
Absolutely good point I find using trains useful for simulating strike action and blocking Paignton level crossing and station throats
Debundling routes from trains has been a long standing wish from me in TSC. But I can always remove RailVehicles and its associated folders from the DLC to get rid of old and obsolete Kuju, DTM, TBT etc to reduce clutter in the train make up. Or substitute higher quality motive power and/or better looking cars using various tools. Or even make up my own Quick Drive consists. In console oriented TSW this debundling probably isn't so easy and sort of breaks the philosophy of easy to maintain ready to play games those consoles are king of. A rolling stock DLC still needs to have layers for every possible route, and a route still needs to have paths and patterns for every possible train if the console player wants to run Thomas on a TGV schedule just for the fun of it.