Well, the city is being physically recreated, starting next week.

To the larger question of why keep it on the map the rest of the year? Few reasons (just my opinion): It's easier than recreating from scratch; folks like to look at it the rest of the year; the land isn't reused for other purposes the rest of the year; precedent of OSM and other maps keep it on the off season.

Year to year, there are a variety of things needing to be deleted/re-positioned/updated, like specific camps, and art work; and updates to the naming of streets, the man pavilion, and temple. 