Well, for one, if the ice hotels were permanent it would go from "The Ice Hotel" to "The Puddle". I'm sure the sand would last a little while but erosion would take a great deal of it away. Also, if you keep a special thing like these hotels in a certain place and you are able to preserve them, they wouldn't be as special anymore. You just lose interest and when you walk down the street with your friends you just start saying, "Oh, yeah. Look, somebody's tongue got stuck again on the ice on the door. I guess they'll just have to call the Ice Police." See, you just start getting used to it and that's probably not one of the people who build these things goals.