I live in a completely different city, a post-soviet one, with dense streets, 9-storey apartment buildings. But still it's hard to socialize. It's the same both in the center, and on the fringe with large micro-districts, where the density is the same, but people are less in haste, and there are less strangers. Same way, people are avoidant.
Like in subway you pretend that others don't exist, and it's hard to get closer with people. It can take months or years to start saying hello to a kiosk salesman you recognize. It's hard to get past by hello with the house neighbors. If you make steps forward, people are unease. Sometimes others are too quick with their steps, you get unease.
The most compelling theory I know is that you need to meet people occasionally, without intention, to deepen the relationships. If all your communication with someone is intentional, I guess, this feels awkward for both sides. I can confirm this from experience: living in a 80K town, I'd walk down the main street to the little shopping mall with a local supermarket for groceries, and would meet people I knew, or friends, and sometimes we'd go walking by the streets, with groceries bag in my hand :) or we planned to meet in 15 minutes. Or go to each other's home. This is hard to replicate in a big city, where even if you see a friend, he/she is usually in a hurry.
Near apartment blocks, there's no porch or garden or park, and even where there is one, I don't see locals sitting there regularly. People are very cautious, even suspicious of benches, because if there's a busy street nearby, once in a year there'll be a group of noisy young people sitting late at night, or one drunkard in a year, and everyone will get pissed off and want the bench removed. (If they allow to install it at all.)
Looking at some places, I theorized that maybe there should be a place where you could sit and let's say play board games _near_ those who come in and out. And of course, it should be indoors, because winters are long and cold. But But I'm not sure of a communal place indoors either. It could become a magnet for homeless, it can be a magnet for just the slacker drinking old men, and repel the rest of people. I've seen too many communities become place repulsive for "normies". Maintenance is a big question too.