With the release of TS2021 came the new and improved Workshop tab that allows us to download scenarios in-game. It's actually a quite decent implementation, so a similar system for Workshop routes would be very much appreciated. If it was to be implemented and I was DTG I'd take the existing scenario tab and put it, along with the routes tab, in a brand new Workshop section on the main menu.
So long as the scenarios were also in their own section that would be fine. I would hate that every time I wanted to select a scenario quickly I had to make sure I had all the reqs first.