Now many college grads have room mates… and I’m not talking about 20-somethings.
As you say though, a lot of furniture is sort of irrelevant. I have a decent-sized house (about 2000 sq. ft.) but don't really have a good place to put a large enough dining room table for more than a small group. My parents regularly had dinner parties for a dozen people in a formal dining room.
I do have moderately-sized groups over now and then but people either eat on their laps/at the coffee table in my smallish den/living room (old New England farmhouse which has been opened up somewhat but still tends towards smaller rooms). I have a couple of big heavy pieces of furniture from my parents but they're just out of the way upstairs to essentially store stuff. The main reason I even still have them is that they're out of the way and provide some useful storage.
Many of their kids, people in my peer group, are in their 30s to early 40s now and still aren’t married and don’t have kids and don’t own a home.
I’ve got a family and a house and I still wouldn’t want any of the old, quality furniture my parents have. It’s just not anything I have a need for.
Another reason is, the craftspeople to maintain this furniture is much rarer. I have a dressing table that was my great grandmothers. It's a beautiful piece and solid as a rock but it's showing wear and tear of daily use every day of my life (and who knows when it was previously restored). Finding someone capable of restoring it is hard, and it's a long manual process which would cost substantially more than buying a new piece. I'll never part with the thing but I doubt I'll ever get it restored either.
My mother has an old settee that was her aunts. It's falling apart needing new springs and upholstery. She's been on a waiting list to get it repaired for years, and the upholsterer isn't taking more clients as he's past retirement age and now does it just a few days a week with a backlog of years.
And it’s fun!
And there's always the risk that someone used Pledge (or something else with silicone oil in it) on the piece in the past. Which you won't discover until you get the first coat of new finish on and get fisheye.
Upholstery, at least, can be fun. A lot of upholsterers do reupholstery work, and many are quite good at it. If at first you don't find someone who can do tied springs, keep looking; they're out there.
I think the implication you're making that previous generations had much more living space is false. My grandparents lived in a rural area in a pretty small home with one bathroom. If you look at 50s tract homes, they're all small by modern standards.
> don't have ROOM
These are not the same.