The arbitrary transition from green to brown on the old maps, when in reality, there is no such transition, is the real problem. When navigating by foot those shapes SHOULD be accurate; I care less about the legal boundaries of the exact park and more about what i'm seeing as I walk around.
Why do you care that the map represents the green parts accurately? How does that enhance your walking experience?
IMO 99% of the time people use maps to get to destinations, so maps should be focused on destinations, not shapes (insofar as the shapes don't prevent you from getting to your destination).
The shape of e.g. a wooded area can be important for orientation when on foot.
But really, maps are nothing but shapes (streets, waterways, coastlines) that constrain navigation on the ground, so it's difficult to make sense of your proposed focus on destinations to the exclusion of shapes.
My scout leader always taught me "never navigate by woods". The reason? It doesn't take long to chop down a forest and invalidate your assumptions.
I remember taking part in 2-day team orienteering competition. We had walked very accurately on a bearing to where the checkpoint should be, but it wasn't there. My friend had taken the bearing on the corner of a wooded area. Looking more closely at the wooded area, we could see a large area of tree stumps next to it...
(We reorientated ourselves, found the checkpoint, and came second in the competition.)
