Me and my daughter watch house finders sometimes.
Yep, even she asks that same thing!
I have an anthropology background... and we even had a class on architecture, because, it does reflect the cultural ethos of a region/culture/people. My Husband, being from Europe, he finds our open space planning, a bit irritating at times. Because where he is from, it is not so open nor intermingling between the rooms. Each room, having a specific, purpose, and walls and a door. But here, spaces are open and thus, the people's activities in it, can intermingle all at the same time. And the kids too. He's not so used to that. But has had to adapt, to that.
Big "master" bedrooms, is typical in the U.S. It is a bit of a "show off" symbolic thing. Status. Comfort. Lushness. Being the king of your own castle type thing.
But sure, no one spends their entire day in their bedroom. And for some places, a bed"room" is not even a room. It is a multipurpose "family" room, in which they do things in it AND sleep in that same room. At night. The entire family.
But here, bedrooms can become a bedroom/tv/spa place.
But historically as well, the bedroom of the "Master"... was very palatial. Due to their being a "King" or royalty.
It denotes... a person and their status. And they did sleep in it and do their daily reigning of their country in it.
It is the bedroom of the "Master."
ie: Master Bedroom.
Then, couples want a big room and BIG bedroom closets.
Big closets too... are very integral, right?
ie: in those reality shows, the entire show can be IN their closet.
No doubt, people also want bedrooms/closets the way they see it in those over the top reality shows.
Media, influence.