I think I would love the idea of downsizing into a tiny home like this, especially if I lived in a bigger city or closer to it as you mentioned. I love efficiency and I'm in awe of the creativity used in creating them!
However, I'm based out of the Midwest, and in many places out here it is hard to just walk down to the store and grab a coffee or base most of your life outside of your home in public common areas.
That being said, land is cheaper, and in turn, house prices are as well. Working on the reducing the old carbon footprint in other ways...maybe one day that includes solar roof panels or other efficiency measures.