We all love variation of what we see while driving. I know that all wagons can't be included on every route, but at least DTG should make them available when we own the routes. Make them appear randomly on consists. Some wagons have differences and could conflict with the lenght of the train but this could be solved grouping them with types, size, era, etc. I loved the TSC wagon packs, I own a lot (steam and 3rd party). But I don't think it's good enough to buy a pack and only see the wagons in the services/scenarios included.
This is something that used to work on Oakville Subdivision, as random freight cars from every other US route you own would sub in. So the basics of such a system is there. But it is not perfect, because apparently in this case the freight cars can't spawn with load enabled, only in empty state - therefore all other routes are not using this system. But I agree, this is something that could be really improved. Mixed consists could work randomly, where the consist info only says maybe the length or the maximum weight of the consist, then it just gets randomly generated afterwards. Would all much more color and variety to mixed consist freight trains.