-Map design: Thats Larian's design there. Honestly im not for or against the idea of having 1 map vs having 5 smaller ones that combined form the same map. They could break it up but honestly, whats the point? What would you gain?
Space. The final frontier. These are the voy... Wait, sorry, got sidetracked.
Anyway, the point is space. Right now, the gobbo camp is literally just a football field away from the "secret" druid grove and in between them are a dead village that gobbos have taken over. Take the wrong exit and you end up in a swamp that somehow manages to exist in the same climate as the rather dry village or the reasonably vibrant forest right next to the village that somehow hasn't grown into the village despite nobody holding it back for a very long time.
If Larian had used multiple maps then these things could exist independent from one another rather than physically right next to one another. And the respective maps could then have a bit more room in them as well. Imagine if Baldur's Gate 2 had placed Trademeet, Umar Hills, the Shade Temple, De'Arnise Keep, and the Exit from Underdark map in pretty much the same place, right on top of each other. That wouldn't have been all that immersive, would it? Same problem we're seeing in Act 1, really.