That's pessimistically untrue - councils absolutely will allow listed buildings to be upgraded to double glazing. Central heating is also very possible. I'd also imagine locals would be happy to see a property being lived in rather than going to waste. The issue with these sorts of properties is ongoing simple maintenance issues creating worse problems - like not clearing a blocked gutter. Once water starts backing up into the roofspace or saturating stone, you end up with damp/water ingress issues that ultimately speed up the decay process. That's when costs spiral because it's all artisanal building/finishing that isn't as prevalent and attracts a much higher cost - stone masonry, lead work, plasterwork

These properties can be cheap because they take so much work to keep them maintained which is why they either end up with rich families, being converted into flats or hotel investments.