I think it's too late to change that
That is not exactly true and i believe that skilled modder would be totally able to cut whole map into smaller hubs with some screen message telling you something like "you were travelling for 3 days in a forrest".
Basicaly all you would need to do would be cut whole map into separate hubs ...
And then add borders in between them, just as they are on Mountain Pass, or Shadowcursed lands entering zone.
If you take Blightened willage for example:
You cut it on North there where Goblins have that bridge conecting it to their gate ...
You cut it on East there where that broken bridge is ...
You cut it on South there where that drained pig is ...
And you cut it on West there where you fight those two Goblin guards ... maybe +/- few metters around, so there is some space.
Ten, once you reach those borders message with traveling appear ...
And then your group is spit out on other side of that border.
Its clumsy i know ... and could be done better ... but that would require assistance from larian wich would need to cut the map acutaly to those pieces and add some "filling" in between them.
What's the point, really? Player convenience?
Pretty much ...
That and Multiplayer. :-/
I mean, i know that this game is not ment for our group to go separately, but that option is there ... so the game needs to be prepared for that.
So while one of your party can decide to go to Swamp, other one can go to Risen Road ... that would be impossible if the game would not allow you to move acros whole map.
It also seems that Larian favour much more single long loading before the game, than MANY shorter during play.