I largely agree, although the places that generate and receive bulk freight tend to do so for a period of decades so there is a reasonable predictability about what the flows might be.
Wasn't the choice between these two routes influenced by freight as well as passenger issues? All the freight on Woodhead was end-to-end and could therefore be diverted to Hope Valley, but the Hope Valley freight originated at places along the route so would have been lost if it closed. Combined with the Hope Valley serving some intermediate population and Woodhead passing through empty countryside, I believe the correct decision was made in that case.
Indeed, although my point is that to begin with, it was the Hope Valley which was selected for closure based on the amount of traffic using Woodhead at the time, which illustrates the folly of trying to base the long term shape of the network around individual freight flows. You end up with a limited network which isn't able to respond to new or changing flows.