I am fairly new to the game, when I realized after searching through a few buildings that the apartments were empty, it dawned on me that this automatically makes them a great place to hide crates and barrels. You do not need to build gates with locks if all the other players realize that it could potentially take them hours to just happen to find the apartment where someone may be hiding something, meanwhile no spawned loot is there to pass the time. If loot did spawn in the apartments that would end the usefullness as a good storage area for stashes as players would have more incentive to go through each and every apartment and thus easily find your stash. Empty apartments make for a better stash spot than building a base in my opinion. Just remember your apartment location, and don't let anyone see you going in or going out. (having to scope out surroundings adds to the excitement)