In order to develop pedestrian-friendly regions, they were given the maximum restriction of 1/4 mile. This size restriction would promote the use human-powered transportation  (i.e. bicycles, skateboards, or even just plain walking.) The distance between regions is reasonably walkable, but are interconnected by the mass transit system.

The higher the density of occupation a region would translate to a more affordable region, + a more sparsely inhabited region would equate a higher real estate value.