I believe the grid in Manhattan is more of a practical construct than anything else, with the influx of people in Manhattan, more space was needed, so a grid was created to protect that space.  The unintended consequences however was that too much land was developed creating a lack of public land.  I believe this was necessary to make Manhatten inhabitable and was a necessay evil. I also think that more cities should use a grid, while still maintaining the balance of protecting nature.