I'm sure the popularity of the open concept is part of the "informality of daily living" that people enjoy now.
In my youth, the kitchen was the center of the home as it still is, (during parties people still gravitate to the kitchen) but still the mother was the slave to the kitchen while everyone else had moved to the family room/dining room to do homework, watch TV etc.
She was isolated from the kids she needed to watch over and from the family interactions. Men rarely or never cooked in the kitchen, maybe did some BBQing but only went to the kitchen to get a beer from the fridge or to eat.
Also the kitchen housed the dining except for maybe 3 times a year. Christmas dinner, Easter Dinner and maybe some family get togethers went to the dining room.
The dining room table was often covered with school book and other "junk" and the living room had the good furniture in it and was only used for company. And some people's furniture was covered with plastic.
Later in my 20 the homes had an entranceway and to the left was the dining room...never used, and to the right, the living room almost never used, and all the action was from the kitchen or the family room.
In my 40s I started to see the cathedral ceiling appear in a lot of higher end homes.
So I guess the natural evolution was open floor plan to join the kitchen, family room and dining room with an added island to eat at or snack at. Both adults can cook if desired and they are both present for TV, and all interactions.
If you want to be alone go to your office/spare room, or to the bedroom or outside deck if weather permits.
This is the way we've been living for the last 30 years I guess.