Different People, different tastes. The Paiseley Canal line isnt maybe the best choice for a standalone dlc, but would make the map more alive. As said many times, i just think the potential of "routes" is not used at all currently, but they have improved with Rush Hour and its A.I services. I just go a step ahead, it can also be a mixed solution: Cathcart as local line, extended with Glasgow Central to Edinburg Waverly incl. Loco. This way Glasgow Central is busier with actual services to run, instead a.i only. Somebody can arrive in Glasgow after a Cathcart Run and go into a Voyager to run a service to edinburgh. ScotRail is just an example, there is plenty of possibilities to come away from the "a to b style".