For the railroads that understand it, they realize that these days, to most Americans, the railroads are invisible. So steam excursions put a face on the railroad. NS and UP really get it, as for CSX, they remain invisible. The good will that the NS and UP get from their runs is priceless.
Is it truly Priceless for the railroads? Do they really perceive any kind of value for putting money into running Steam on their railroads? Or, at the very least, risking a breakdown on a heavily-traveled freight main line?
I don't understand how most train fans and model railroaders do not understand that railroading is a simple business. Railroads got out of small less than car size loads a long time ago in favor of unit trains and container traffic. That alone should tell you exactly what they're really thinking of and the things they truly value.
Naturally, there are railroads that will allow Steam on their lines. But in those cases, even then, the most understanding railroads wouldn't allow it with a great frequency. As much as we think it is great that Union Pacific runs their own steam, we have to remind ourselves that they don't run Steam very often.
I'm not saying that railroads are heartless and evil corporate greed Hogs, but they are simple businessman. We shouldn't get terribly upset at them when they don't want to run something that doesn't provide the income that their large, long trains do.