New player here with a possibly dumb question. Why are all the areas so unbelievably huge, but also so unbelievably empty?

I am fairly new to the game. I played once long long long long long ago but it's been so long that I don't really remember it at all. I'm loving the art style and the lore and everything, but one thing that I've noticed that's really weird in every character that I've started is that all of the areas seem to be massive like Big beyond belief sometimes in a good way, but then they are also absolutely devoid of anything. Absolutely empty. The outside world seems to be sprawling nothingness with a sprinkle of enemies, and even some city sort of locations. There seem to be a lot of NPCs that don't do anything? Maybe I'm not the right level or something but they're like trainers and stuff that don't do anything. Even if location that I was so excited to get to because it's absolutely beautiful, ironforge, mostly because I loved dwarves, was just desolate. What's the deal? The only thing I can think of is that they made them big to support a lot of players.

Again, sorry if this is a stupid question, it's just been a long time since I've played this game and I don't remember everything being so empty. It's been several years mind you. And it's not really empty as in not a lot of players, will I guess it is, but I'm just mean the world seems empty. Or perhaps I've just been spoiled by modern games and this is normal lol