Definitely something I missed in Dark Souls. While it has the more visually impressive areas, most of them just feel abandoned, where in Demon's Souls, the first level of Tower of Latria makes you go "Jesus Christ, what happened here?" It's a vibe that I hope Dark Souls 2 can balance better along with the impressive, expansive locales.
While I see the difference, I like Demon's Souls' equally as Dark Souls', but still prefer the latter. I think Dark Souls had a good compromise, it still had some opressiveness (okay, maybe it could a TAD more) and it had something much better than Demon's Souls: a reward for exploration.
Dark Souls' locales were much more beautiful, magical and detailed and so exploration in itself became a reward. For instance, I distinctively remember going to Ash Lake in nearly every single of my many playthroughs just because of how awesome it looks and despite not having nearly anything to do there. In Demon's Souls stuff was more like "this is messed up, well, moving on" and that's great, but it doesn't awe me and make me wanna go back just for the locale itself and look at it and think "this is awesome, lemme look at it". (also, many areas felt like giant barren corridors in Demon's Souls, but that's just level design, not so much the art style)
Tl, dr: Dark Souls' areas are haunting while being beautiful and sort of become a reason in itself to propel you forward through the game in your first time and in subsequent playthroughs become a reason to revisit the game.
But almost all of the NPC dialogue in Dark Souls is already optional. You don't have to talk to anyone except the shopkeepers and one or two other NPCs. You can miss all of the other interactions completely. Furthermore I don't think a city hub is something From Software would do, personally. When another poster mentioned other non-combat zones I was thinking more like a small tavern lit by lantern on a cold dirt road in the forest. It'd be a place to stop and rest, maybe interact with a shopkeeper or whoever happens to be drinking that night. I think it'd be a small, cool way to build atmosphere and add character to the game.
I agree with you on the no bustling cities, though. That'd just be dumb.
Yeah, they are all optional in Dark Souls, but it's because the NPCs are few. If they added a lot of NPCs/dialogue, some of it would end up being non-optional, just for the sake of making it useful/showing off. Also, as I said, they either wouldn't say anything interesting or they would and then the storytelling method would change from its usual, cool, subtleness.