Not sure what the expectation people have here is: something like Skyrim? That gets tiresome after a while.
That's not really the point. Its not about having a constricted space. Yeah, when you are in a ravine you don't expect endless plaines on all sides. The point is that the whole world is made like a game, filled up with encounters to the point that you just walk from one to another, but not in a good way. You don't discover anything on your own you are spoonfed depending on wheter you go left or right. It simply doesn't feel natural. Compare it to especially BG1 - though I admit they had it a lot easier as creating those maps took significantly less time so adding open spaces with just natural wildlife was easy.
The more I think about it the more I feel BG3 is build primarily to be played in a group with friends and not as immersive singleplayer experience. In a group, where you will always be doing something or 'creating' downtime talking with each other regrouping and stuff like that, this type of map works endlessly better than BG1 - and that's most likely the reason its build this way. Just think about the alternative - having small hubs connected through world map would mean a lot more loading screens. And to tell all stories and give them their own natural space on the map would need to be a lot bigger maps (which might also affect performance depending on how they structure their asset streaming)... so all in all it now makes sense to me as many other decisions around this game do. Doesn't make me satisfied with the result, but I get the logic behind it.