It's not very popular in the US but multi-generational housing has existed for thousands of years in other parts of the world and solves for this, even while renting.
I don't think it "solves for this"... Those types of units are not cheap where I am and they're rare. It's not like you spend $100-200k and suddenly you have a suitable multi-generational home. Where I am - it's going to be at least $1m-2m extra. The kids can't afford that in a mortgage - let alone cash that a remodel would require.
Sure it does. It just might not work for you. I can certainly respect that everyone's situation is different but I do think your original comment is highly Bay Area biased. There are plenty of other (better IMO) areas that are more affordable, including New York.
