alt Hacker NewsThe initial idea was to first sell 50% of the land and then sell the other 50%. [1] Thanks to corner crossing, the checkerboard pattern made sure that owners of the first batch wouldn't be cut off from their access by buyers of the second batch.
[1] From TFA: "This checkerboard pattern allowed the government to keep all the undeveloped sections in between and wait for them to go up in value before turning around and selling them to developers".
I think that's more than likely just a fig leaf proposed for and by the people that planned to try to only have to by ~50% of the land they actually wanted to enclose. So much of this land is too far away from anything for much meaningful development.