While I agree that stealing is a game mechanic, there is currently no way for us to defend against it. It's a one side victory for the thief, and it drains our supplies like hell. We can currently:
1) Blow there heads of with arrows IF we find them.
2) Set up poor walls of unfinished baskets, in which can be instantly destroyed
And that's it.
What I suggest here is one of two simple ideas being implemented.
1) A guard tower that spawns two guards, with 30 melee and 30 archery. The tower can be set to tell the guards who to kill, and then they will do it on sight. The player would be responsible for equipping the guards.
2) A guard tower that automatically fires arrows at anyone that it is set to kill. It would fire at the same rate as one archer, and would take half the time to build as the previous one.
Now both these towers should have around 500-800 hp, so they can be destroyed. Each should probably be about the building requirements of a house. You should really take this into consideration loftar and Jorb, otherwise we just get stolen from and that's that.