Gee dragon, you have great logic... Lets make drawers and chests useable, then make them so you can lockpick them, then make them so you can't lockpick them...
If they make chests and drawers useable, just have a basic security on the chest/drawer that is like equal to your level. So a level 5 guy puts stuff in a chest, locks it. A level 4 thief would not be able to steal it.
Or better yet, base it off of mental experience or something... as the smarter you are, the more clever you will be to lock away your stuff.