1. Could view it as a cultural thing. For example, some cultures might embrace minimal personal space. And, the media keeps talking about the "tiny house movement."
2. Everything is relative. I personally opted to buy a smaller house than I could afford, and I generally try to live minimally.
3. In general, it's better for the collective good (less waste) to move in that direction. That said, technological advance might some day allow every human to live in a McMansion.
Also remember that there isn’t a big difference between tiny houses and trailers. Imagine turning SF into a trailer park.
But there is a huge difference between a minimally viable shelter (electricity, plumbing, standing room, privacy) and a car or a capsule. Where exactly do you have sex? Vomit when sick? Keep a pet gold fish? Cook? Poop? All of that is possible in 400 sqft apartment and not possible in a car. So it’s not quite relative.