I totally get your point, Max. The last time I had cleared everything out, it felt REALLY weird. I really felt like the world was dead. I felt almost saddened because it was SO quiet everywhere. Especially after the tieflings leave the grove, it gets REALLY quiet. It's like nothing's alive anymore anywhere.
Something like that is fine for a place like Grymforge or the Dank Crypt or even the Goblin Camp/Selunite Temple Ruins, but when you're roaming the forest or the road or the bog, that's when I feel it the most.
I honestly think that the world would feel more alive if they even just put more animals into it. Even if the animals flew off or scampered off or something, at least the world would feel more living and animated. Even if you weren't able to fight the animals or whatever, just having SOMEthing alive and moving would make it feel a bit less like a scary ghost town after you've cleared it.
So, I don't know if random encounters is the best solution, or if we just need more SOMEthing alive on the map. I do still think that IF they could pull off random encounters well, that would be good - especially for places like Moonhaven where it makes sense that goblins would replenish their numbers there after a few hours or a day. It's still very weird to me that they don't. I mean, as a DM, if my party rested and came back to Moonhaven after clearing it the first time, I probably would have some sort of patrol milling about looking for whoever did it.
But I can also see that places like the bog or the road, it might be a bit weird to trigger random encounters. I don't know. Again, I guess if they did it well, it would probably make the game more fun and exciting. I think I'm just starting to doubt that it would be done well, and the last thing I want is a bunch of boring random encounter trash mob fights.