Cooking is also less frequent, extraction fans are better/cheaper, we don’t use wood burning stoves. When people do cook it’s less likely to be an all day process, and less likely to involve methods like deep frying in bacon grease. It’s also less likely that a middle class family has a servant to do the cooking for them.
All this leads to less need to segregate the kitchen from the rest of the house.
If you look at Victorian houses, kitchens were placed as far away from living spaces as possible. Going forward from the 19th century there has been an overall trend towards integrating the kitchen with living spaces. Culminating in the modern trend of combining the kitchen and living room into one large space.
Families are also smaller than they used to be, so there’s less need for as many rooms. Plus furniture is larger on average.
The point is there are factors pushing houses towards larger open spaces, and larger open rooms in general that are likely durable.
That especially is just fashion, I'd be really careful with that sort of conversion. Or, if the only 'problem' with a property is that it has too many segregated rooms, and that's depressing the price.. snap it up, fashion's bound to come around. (Unless it's for you to live in and you particularly care of course, live where you want!)