It's come a full circle . . .
If one goes back into history, most kitchens were large relative to the size of an average house for two reasons: firstly, this was where the family generally gathered, and secondly during cooler weather it was usually the warmest room in the house. So it made sense to have plenty of room for a large table that would accommodate the whole family.
One exception to this situation was the homes of wealthy people, where kitchens were larger than average but not by a lot. Instead, they were surrounded by lots of purpose built space for associated functions, like large laundry rooms, mud rooms, breakfast rooms, and butler’s pantries. The idea of these areas was that servants would take care of most cooking, cleaning, and serving, and the homeowners wouldn’t spend much time in the kitchen. These homes generally had large and gracious living and dining rooms and nice entry halls.
During the mid 20th century, when massive numbers of tract homes were built in the US, it was much more fashionable to have formal living and dining rooms and a den or family room than to have a large kitchen. Part of this was driven by a desire to appear more affluent, and part by a feeling that with new labor saving appliances like freezers and dishwashers a housewife didn’t have to spend so much time in the kitchen so it should be efficient above all else. For a few decades this approach probably worked for many families, as a woman who didn’t work outside the home had time during the day to take care of most kitchen tasks.
Starting in the ‘70s and ‘80s when the two-income family became the norm everything changed because all kitchen duties had to be done after work or on weekends, which is when families spend time together. All of a sudden those small kitchens became bottlenecks as a whole family would crowd into the room. This in turn led to the current practice of combining the kitchen and family room into a “great room”. I find that to be a really annoying builder-esque term, but these sorts of spaces really work for most families. Formal rooms are still important in some markets, but homeowners seem to be more realistic today about what works for them and will often accept a smaller living room in exchange for a nice large kitchen.
Another factor is the influence of modernist architecture on floorplans. Most new homes today have floorplans greatly influenced by modernism, even if the home has traditional detailing and materials. This emphasizes open spaces and dovetails into the need for multi-purpose kitchens that provide for more than just minimal meal preparation space. The photo below is of a house I designed a few years ago. The kitchen is fully open to the family room on one end, and there’s a large island which is the preferred arrangement for many people. Beyond the peninsula on the left is a small breakfast nook with french doors in a bay window that looks into the back yard. This house has good formal living and dining areas, but I’ll bet that whoever owns it now spends most of their time in the kitchen and family room.
