Matt Yglesias makes it:
It seems to me that human beings have some kind of psychological tick that leads them to overestimate the amount of time they’re going to want to spend engaged in outdoor recreating. It’s one thing if you live in California, where the weather’s nice all of the time, but here in the Northeast how much use do we really get out of parks? People don’t go to the park at night, or during the winter, or when it’s raining. Compare that to, say, an apartment building with some retail on the ground floor. People go to stores all the time. Obviously, that’s not to say that an ideal city would have zero parkland—parks are nice. But it’s not clear to me that we’re suffering from a park shortage. And in environmental terms, it’s much better for the planet to construct additional housing units in already-urbanized areas than to pack a bit more green space in the city and have more people living in sprawling exurbs.
I have a hunch his thinking might change if/when he has a kid.