Well written. Straight to the point. When poor is a rat race and no room for risk. Any mistake and you're done. Even if you see opportunity you can't afford to try. And hopelessness.
Barcelona's blocks are nice but won't work as a mostly pedestrian self contained urban unit. People have to work and get social services outside those blocks.
If you scale them up a bit, add infrastructure, add workplaces and make it 10-15 walking distance and add public transit links to other such places that will do it.
USSR had implemented this idea and it worked fine while factories / companies were providing accommodation in the walking distance along with all the necessary services - schools, hospitals, kindergartens and shops.
I doubt that it would work in a modern Capitalist society unless we all work from home.