Dead ends can be used to block off directions you don't want the player to move in, e.g. you can use a dead-end with only one exit to the south to block an exit pointing to the north, east or west. However, that's too easy to miss and should be made clearer during the tutorial. I imagined it to be a more interesting choice for blocking off exits than the no-exits-tile as the player might turn around and arrive at a position adjacent to an already placed tile in which case an already placed (but still unvisited) tile becomes really dangerous. Admittedly that's hardly relevant at the moment though as most players end up building in a (more or less) straight line and never turn around.