So um, why are the houses and nature mutually exclusive? I live in a suburban detached single family home, and my whole neighborhood is filled with trees, wildlife and even a tree lined creek that separates the back yards on my street from the back yards on the opposite side. You can't even see my actual yard from google maps because it's nearly entirely covered by tree canopy (at 6pm in summer my yard is 100% shaded). We have all sorts of wildlife including deer, foxes, owls, frogs, mallards, rabbits, squirrels, etc.
While I agree that we do need more housing options of all sorts, I don't for a second agree that nature and suburban housing are mutually exclusive. We just need to stop tearing down all the trees when we build, and plan better.
Don't forget the huge energy savings (heating/cooling, transportation, infrastructure) by having denser housing. It isn't just a measurement of "I can see trees," but all the daily human activities that have a reduced environmental impact in denser development. It's counter-intuitive, but rural areas that are "nearer to nature" are often worse for the environment.
There is probably a break-even point, I don't think everyone living in skyscrapers is ecologically ideal and I wouldn't want to live there anyway. But medium-density development with multi-unit (shared wall) buildings allows huge energy costs, while also making public transit more viable and providing a tax base that actually pays for its own infrastructure.
I think the point of the island is to show that when you have limited space, residential density really matters. Even if you took away all the concrete, spacing, etc between houses in this example and just out 100 ranch style homes in a corner with no spacing in between them, it would leave room for significantly less nature.
Your neighborhood sounds beautiful, and that's great, but that ratio between nature and residents is probably being achieved with more land than if high density residential housing was in place.