I always read these stories about cities rezoning to allow micro-apartments with mixed feelings.
On the one hand, I absolutely think that people should be allowed to rent or buy a micro-apartment if they want to. Lifestyles are changing, family structures are changing, and in a country of 300 million people there's certainly room for some people who'd like to live in very small apartments.
On the other hand, it's incredibly frustrating to see cities reaching for this solution when there are better and more obvious ones at hand. The implication of the micro-apartment movement is that the crisis of middle class affordability in major coastal cities is that people can't buy the steel and concrete. Rural housing affordability is actually like this. There's almost always some cheap land available in small towns, so what separates the rich from the poor is literally how much house you can afford. Fancy people live in fancy houses that contains lots of physical building material. Poor people live in little trailers. If you're less poor, you get a double-wide trailer. If you're too poor to afford a trailer, a "micro-trailer" might help. It's like how a sub-compact car is cheaper than a full-sized SUV.
But this is not what the middle class affordability crisis in San Francisco or Manhattan is about. It's not that families can't afford the construction material that would be required to get them a decent-sized apartment. It's that you're not allowed to build enough apartments to fit all the people who'd like one.
Most people I'm familiar with want the city they live in to be a great place and aspire to make it an even greater place. But if your city is great, people will want to move there. And if real estate developers aren't permitted to add more and bigger structures, your desirable city is going to become a city nobody can afford to live in. Slicing the constrained building stock into smaller and smaller apartments will help some single people squeeze in at the margin, but it doesn't address the underlying dynamics.