Would love some more buildings but they should be optional. Like in New Leaf, where you didn't need to build a café, Katrina's tent or Resetti's office.
Visiting NPCs don't bother me and it's something that works well for some of them. I love Leif, for example, but the amount of things he sells is better suited to visiting than having his own shop like in NL. I also love KK Slider playing on the plaza, it's a lot more chill and fits the island vibe perfectly. It keeps things from getting too crowded too. We don't have a dedicated shopping area so having pointless buildings taking up space would be a hassle. I'd be fine with it if they made it optional though.
There are definitely NPCs I wish would have their own buildings but that's NPCs or features that aren't in the game (yet). I really want Brewster to come back and have a cafe and I wish Celeste would get her own observatory, though I'm just happy she gets more to do than she did in NL, at least.