Don't like this option making the game smaller this far after release is like a slap across the face.
While I don't take it quite as hard (mostly because I intend to walk this back through modding), I agree this is an undesirable and confusing move. My pea-shooter laptop which has earned the derision of nearly everyone who hears of it could handle an insane map with the number of objects turned up. Making the map smaller to make it more dense is a step in the wrong direction: I would make all maps more dense, and let those of us with weaker computers use smaller maps. For the "biggest 4X game ever," becoming smaller makes little sense.
I don't want to seem ungrateful, because this update really was a monumental effort, and one that has restored my faith in the future of GC3. I would, however, prefer to see changes moving forward that expand the game as much as possible, rather than limit it.