While I would hate to lose actual trees, I'm medium on the idea of this on it's own. People need lots of things and space, which causes the removal of trees. If we can replicate some of their functions, such as CO2 absorption with this tech, then that seems good. If upkeep is the same as a tree, I don't see a downside to the overall concept.

My thought would be that this shows up on top of the buildings instead of at ground level, though.... Plant real trees and put these on the roof. The real loss would be if we stop making green spaces because these things meet the need for O2. Green spaces in cities do way more than just clean the air, though, so I'm not sure we're that dystopian yet.

The photo looks like it doubles as a bench too, so maybe that helps justify its footprint. Make them a mini-light show with varied colors and it can become a functional art installation. How long until it has spikes to prevent someone from taking a nap on it, though?