But there is a whole spectrum between the densities of super low-density rural Tennessee and hyperdense NYC-like places and I find the ideas for something in-between are largely unexplored in practise because of various reasons.
The argument of closeness of amenities prioritizes a consumption-based lifestyle over building good nests for humans (and little humans) to actually live in. Let's take your example, where you said people don't like to walk 1 km to a small convenience store -- is the assumption somehow that walking 1 km to reach the tiniest park is something people would like?
As for jobs, I'd say very, very few people live in a city next to their jobs. They have to commute in one way or another. This seems to fall mostly between 10 minutes to 60 minutes when discussing with people. Time-wise I'd say this range is aligned with a smaller town/city (either a job in the town/city, or in another town/city).
And speaking of enjoyment, to be honest I'm not convinced many people in big cities really enjoy it. I'd wager to say that most people generally would enjoy a less noisy and overall cleaner environment where nature is nearer than concrete. Not everyone, but most.
My childhood town (in Northern Europe) is 31 people/km2. It's overall about 80 k people (lots of empty space). Density-wise it's probably something like your rural Georgia but everything one needs is there, plenty of shops and businesses of all kinds and even some variety in restaurants (believe it or not). Quite many people could actually do with a bicycle or a bus, but in practise people have a car because of winters and four seasons and because buses don't run all the time and reach everywhere. So then, for example, most people do groceries once a week and drive that 3-10 km to the grocery store or mall concentrations. But based on my experience, they would likely do exactly the same thing in a bigger city too, since the inner-city core grocery stores are more expensive with less variety.
Also, there's a spectrum between bare grass or wild forest... For example, where I live now one might have a "wild" forest designated as a "park", and someone from the municipality just cuts away the hanging branches, windsnaps and such and ensures the paths don't grow shut. It's very low effort and cost. Once in like 5-15 years they might cut some more growth of trees so there's more sunlight everywhere. This type of "park" does not have manicured golf course like grass areas and fountains and so the per year per area cost are much smaller.
So it's not about the cake and eating it, it's about having a different kind of cake.
Anyway, thanks a lot for the link!
Edit: PS. I followed your link now; the concept of Neighbourhood Park is a neat one. That is kind of what I mean, more of that, not necessarily with golf course lawn. Also, the "John F. Collins Park in Philadelphia" looks great!