If you're staying within the city proper and still have a "very long commute" (which to me is 1+ hours, I'm not sure what the means to you) it sounds like the city is still insufficiently dense.
In my experience, the vast majority of people with long commutes are commuting from suburbs/exurbs into a city center. I'm sure there are some cities that are so spread out that one could have a long commute while still staying within the city limits, but that would imply that there are people even further out with even longer commutes from the suburbs.
I commute through the city, if one person crashes their car it impacts thousands of people getting home on time to see their kids before bedtime, how is that a nice way to live?
As for mental health issues, some people like cities, some don't. Without the traffic it would probably be a lot more pleasant.
It's tough to have a successful small town without it growing into a city.
The maintenance costs associated with the spread-out infrastructure required to support everyone having their own personal 1/4 acre of land cannot be supported by the tax base available in such a low density population. Most US cities could be much denser than they are with a higher quality of life and lower pollution if people could be located within walking distance of most of the places they need to go.