Stop being so negative about the damn thing.
1. There isn't a 100% chance that the picking will succeed. We're not sure what this rate will be yet.
2. We're not talking 20 minutes after you log off, more like 5-10 minutes. If you are a nomad living far away from civilization, there is no way someone can make it to your house and steal your stuff in that time.
3. Picking a chest takes appx. 40 seconds, giving them very limited time after you log off.
4. If you want something to be incredibly secure, just put like 5 locked chests that are empty in a room. Then hide the actual goodies in a secret room. Say the chance that the picking succeeds is 50%, they might need 9 tries before they have looked in all chests. 9 tries = 9 lock picks = 18 gold bars wasted. 9 tries * 40 seconds = 360 seconds = 6 minutes.