I also agree time moves too quickly, but for different reasons than the OP.
I don’t mind that routes take X months, what I don’t like is the speed at which you’re in 2015, it’s far too fast. I would like a modifier so that the game calendar runs at around 50-75% of it’s current slowest.
Even with the small amount of trains, and even smaller road amount of road vehicles, I feel rushed in to upgrading to newer models. I would like to enjoy each era for a much longer time (at least double). Now, when DLC and Mods become more common, it will feel even worse. You’ll be passing decades so quickly that you don’t get to enjoy the transition of the era to the modern vehicles of the time.
I would also like all calculation to remain the same, as this would have little effect on a slower time progression. It would certainly not make it easier, if you’re going to gain money, yes you gain twice as much in a game year if running at half the speed, BUT you still play for the same length of real time as you would normally. With the same token, you’d lose double the money if you’d made a mistake.