I think if you explain the idea and constraints to the user, you can get quite far. The freight challenge said to connect all industries without terraforming, and that works. I messed up in not connecting the secondary industries, as I didn't realize those were supposed to be connected to towns, but I may try that one day.
You can also do a lot by the shape of the land I think or placement of industries and cities. If you put frams at one area, and the factory in another area, the player has no choice but to bridge that gap.
However, for me, much of the fun comes from planning. Where to put tracks so I can re-use them? What industries should provide to where? More pre-cooked scenarios that give fewer options are less fun to me. That may be a personal thing though, other people seem to enjoy scenarios like "rebuild train network of <country>" which has very little choice in planning, if you ask me.
I spend several years trying to make a fully connected industry network, where under control of cargodest, all cargo could go to any industry. Unfortunately, I solved that puzzle, and need a new one