I lock mine just because I hope it helps it seal better,and that way I know its closed all the way. I don't think it would be a problem picking or breaking the lock,since mines a pretty cheap lock. If it were a master lock or something tho it would be a different story.
I like cheeseburgers also tho.
Do you lock up your humidor? Just a curious question that came to me. I have two with locks and I think I have the keys, but have never locked them. Maybe you have a crazy wife or girlfriend, a thieving roommate or sibling? Or the HTF stuff? Have you ever lost your keys with it locked, and can they be picked easily?
I do not, but once Jack is able to reach the key.. yer damn right I'll lock it. heh.