there are lots of activities the game advertises for you to do. Where it fails for some is if it feels like a good time investment + enjoyment while playing...
I agree with the sentiment that i miss something from the open world. Each zone feels disconnected from Azeroth and from each other, i do not feel invited to run around and explore it. And that might be because i already spent so much time in each zone. But my guess: The zones do not offer much besides world quests. Finishing the campaigns felt satisfying, but now the world feels empty for me afterwards.
I also do not get as much atmosphere and variance out of them compared to previous expansions. Shadowlands as a whole has a similar problem as the Maw itself... it is not intended to be the place you want to spent time in.. so in a sense the developers nailed the atmosphere they were going for?