There's a spectrum of density, and perhaps the sweet spot for front-porch interactions is somewhere in the middle of that spectrum. I live in a neighborhood with ample front porches and sidewalks -- and I've heard it referred to both as a suburb (by dense city dwellers) and "the city" (by people who live further out from the dense urban core). But it's easy to imagine both a dense city neighborhood and a semi-rural far-flung suburb with no front porches and no culture of interacting with neighbors.

Even the definition of "outside the urban core" is hard to pin down; I'm pretty sure you could get disagreement on whether where I live is within the urban core or not.