A group of living things banding together into a mega organism is an evolutionary strategy that usually occurs in response to sustained predation by other species. That’s true all the way up from single-cell lifeforms to human beings. I’m not sure there’s a reason to repeat that pattern at one more level of abstraction. You don’t have to go full anprim to have urban design which is ecologically aware or to avoid chopping down the lungs of our planet for extra space to put caged animals.

I’m confused by your assertion that we would have access to nature, but wouldn’t touch it. What does that mean? We would breathe the air. We would drink the water. It’s all connected.